UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ☒                             Filed by a Party other than the Registrant  ☐

Check the appropriate box:

TALLGRASS ENERGY PARTNERS, LP

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

4200 W. 115TH STREET, SUITE 350, LEAWOOD, KANSAS 66211

MERGER PROPOSAL—YOUR VOTE IS VERY IMPORTANT

Dear Tallgrass Energy Partners, LP Unitholders:

On March 26, 2018, Tallgrass Energy GP, LP (“TEGP”), Tallgrass Equity, LLC (“TE”), Tallgrass Energy Partners, LP (“TEP”), Tallgrass MLP GP, LLC, which is the general partner of TEP (“TEP GP”), and Razor Merger Sub, LLC (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”). Pursuant to the Merger Agreement, Merger Sub will merge with and into TEP (the “Merger”), with TEP surviving the Merger as a wholly owned subsidiary of TE and its subsidiaries. At the effective time of the Merger, each issued and outstanding common unit representing a limited partner interest of TEP (collectively, the “TEP Common Units”), except for any TEP Common Units owned by TE, Tallgrass Equity Investments, LLC, a Delaware limited liability company and wholly owned subsidiary of TE, or TEP, will be converted into the right to receive 2.0 Class A shares representing limited partner interests in TEGP (the “TEGP Class A Shares”). No fractional TEGP Class A Shares will be issued in the Merger. All fractional TEGP Class A Shares that a holder of TEP Common Units (“TEP Unitholder”) would otherwise be entitled to receive as merger consideration (after taking into account all TEP Common Units held by such TEP Unitholder) will be aggregated and then, if a fractional TEGP Class A Share results from that aggregation, be rounded up to the nearest whole TEGP Class A Share.

Pursuant to the Merger Agreement and the Amended and Restated Agreement of Limited Partnership of TEP, dated as of May 17, 2013, as amended (the “TEP Partnership Agreement”), holders of a majority of the outstanding TEP Common Units voting as a single class must vote in favor of the Merger Agreement and the transactions contemplated thereby, including the Merger (the “Transactions”) in order for them to be approved and adopted. Contemporaneously with the execution and delivery of the Merger Agreement, TEGP and TE entered into a support agreement with TEP, pursuant to which TE agreed to, and TEGP agreed to cause TE to, vote the 25,619,218 TEP Common Units held of record and beneficially by TE in favor of the approval of the Merger Agreement and the Transactions at any meeting of the TEP Unitholders. TEP has scheduled a special meeting of the TEP Unitholders (the “TEP Unitholder Meeting”) to vote on the Merger Agreement and the Transactions on Tuesday, June 26, 2018 at 10:00 a.m., Central Time, at the Hilton Garden Inn, 5800 College Boulevard, Overland Park, Kansas 66211. Regardless of the number of units you own or whether you plan to attend the meeting, it is important that your units be represented and voted at the meeting. Voting instructions are set forth inside this proxy statement/prospectus.

The Conflicts Committee (“TEP Conflicts Committee”) of the Board of Directors of TEP GP (the “TEP GP Board”) has determined unanimously that the Merger Agreement and the Transactions are fair to, and in the best interests of, TEP, including its subsidiaries and the TEP Unitholders other than TEP GP and its Affiliates, and has approved the Merger Agreement and the Transactions, which constituted “Special Approval” under the TEP Partnership Agreement. The TEP Conflicts Committee also recommended that the TEP GP Board approve the Merger Agreement and the Transactions and determined to recommend that the TEP Unitholders approve the Merger Agreement and the Transactions. The TEP GP Board has determined unanimously that the Merger Agreement and the Transactions are in the best interests of TEP and the TEP Unitholders, approved the Merger Agreement and the Transactions, directed that the Merger Agreement and the Transactions be submitted to a vote of the TEP Unitholders at a meeting in accordance with the TEP Partnership Agreement, and determined to recommend that the TEP Unitholders approve the Merger Agreement and the Transactions.

The Board of Directors of TEGP GP has unanimously determined that the Merger Agreement and the Transactions are in the best interests of TEGP and TEGP’s limited partners and approved the Merger

Agreement and the Transactions, including the issuance of TEGP Class A Shares in connection with the Merger.

This proxy statement/prospectus provides you with detailed information about the proposed Transactions and related matters. TEP encourages you to read the entire document carefully. In particular, please read “Risk Factors” beginning on page 22 of this proxy statement/prospectus for a discussion of risks relevant to the Transactions and TEGP’s business following the Transactions.

The TEGP Class A Shares are listed on the New York Stock Exchange (“NYSE”) under the symbol “TEGP,” and the TEP Common Units are listed on the NYSE under the symbol “TEP.” The last reported sale price of the TEGP Class A Shares on the NYSE on May 2, 2018 was $20.30 per share. The last reported sale price of the TEP Common Units on the NYSE on May 2, 2018 was $40.38 per unit.

David G. Dehaemers, Jr.

President and Chief Executive Officer

Tallgrass MLP GP, LLC

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under the proxy statement/prospectus or has determined if this document is truthful or complete. Any representation to the contrary is a criminal offense.

All information in this document concerning TEGP has been furnished by TEGP. All information in this document concerning TEP has been furnished by TEP. TEGP has represented to TEP, and TEP has represented to TEGP, that the information furnished by and concerning it is true and correct in all material respects.

The proxy statement/prospectus is dated May 18, 2018 and is first being mailed or otherwise delivered to the TEP Unitholders on or about May 23, 2018.

Leawood, Kansas

May 18, 2018

Notice of Special Meeting of Unitholders

To Be Held on Tuesday, June 26, 2018

To the Unitholders of Tallgrass Energy Partners, LP:

A special meeting (the “TEP Unitholder Meeting”) of holders (the “TEP Unitholders”) of common units representing limited partner interests (the “TEP Common Units”) in Tallgrass Energy Partners, LP (“TEP”) will be held on Tuesday, June 26, 2018 at 10:00 a.m., Central Time, located at the Hilton Garden Inn, 5800 College Boulevard, Overland Park, Kansas, 66211, to consider and vote upon the approval and adoption of the Agreement and Plan of Merger dated as of March 26, 2018 by and among Tallgrass Energy GP, LP (“TEGP”), Tallgrass Equity, LLC (“TE”), Razor Merger Sub, LLC (“Merger Sub”), TEP and Tallgrass MLP GP, LLC (“TEP GP”), as it may be amended from time to time (the “Merger Agreement”), and the transactions contemplated thereby, including the merger of Merger Sub with and into TEP (such transactions, collectively, the “Transactions”) (such proposal, the “Merger Proposal”).

TEP will transact no other business at the TEP Unitholder Meeting except such business as may properly be brought before the TEP Unitholder Meeting or any adjournments or postponements thereof. At this time, TEP knows of no other matters that will be presented for the consideration of the TEP Unitholders at the TEP Unitholder Meeting.

Pursuant to the Merger Agreement and the Amended and Restated Agreement of Limited Partnership of TEP, dated May 17, 2013, as amended (the “TEP Partnership Agreement”), holders of a majority of the outstanding TEP Common Units voting as a single class, which constitutes a “Unit Majority” under the TEP Partnership Agreement, must vote in favor of the Merger Proposal in order for it to be approved. Failures to vote, abstentions and broker non-votes will have the same effect as a vote against the Merger Proposal for purposes of the vote by TEP Unitholders required under the Merger Agreement and the TEP Partnership Agreement.

Contemporaneously with the execution and delivery of the Merger Agreement, TEGP and TE entered into a support agreement with TEP, pursuant to which TE agreed to, and TEGP agreed to cause TE to, vote the 25,619,218 TEP Common Units held of record and beneficially by TE in favor of the approval of the Merger Agreement and the Transactions at any meeting of the TEP Unitholders.

The TEP Conflicts Committee (“TEP Conflicts Committee”) of the Board of Directors of TEP GP (the “TEP GP Board”) has determined unanimously that the Merger Agreement and the Transactions are fair to, and in the best interests of, TEP, including its subsidiaries and the TEP Unitholders other than TEP GP and its Affiliates, and has approved the Merger Agreement and the Transactions, which constituted “Special Approval” under the TEP Partnership Agreement. The TEP Conflicts Committee also recommended that the TEP GP Board approve the Merger Agreement and the Transactions and determined to recommend that the TEP Unitholders approve the Merger Agreement and the Transactions. The TEP GP Board has determined unanimously that the Merger Agreement and the Transactions are in the best interests of TEP and the TEP Unitholders, approved the Merger Agreement and the Transactions, directed that the Merger Agreement and the Transactions be submitted to a vote of the TEP Unitholders at a meeting in accordance with the TEP Partnership Agreement, and determined to recommend that the TEP Unitholders approve the Merger Proposal.

The Board of Directors of TEGP GP has unanimously determined that the Merger Agreement and the Transactions are in the best interests of TEGP and TEGP’s limited partners and approved the Merger

Agreement and the Transactions, including the issuance of TEGP Class A Shares in connection with the Merger.

Only TEP Unitholders of record at the close of business on May 18, 2018 are entitled to notice of and to vote at the meeting and any adjournments or postponements of the meeting. A list of TEP Unitholders entitled to vote at the meeting will be available for inspection at TEP’s offices in Leawood, Kansas for any purposes relevant to the meeting during normal business hours for a period of 10 days before the meeting and at the meeting.

YOUR VOTE IS IMPORTANT. WHETHER OR NOT YOU EXPECT TO ATTEND THE MEETING, PLEASE SUBMIT YOUR PROXY IN ONE OF THE FOLLOWING WAYS. If you hold your units in the name of a bank, broker or other nominee, you should follow the instructions provided by your bank, broker or nominee when submitting instructions to cause your TEP Common Units to be voted. If you hold your units in your own name, you may submit your proxy by:

Submitting a proxy now will not limit your right to vote at the TEP Unitholder Meeting if you decide to attend in person. If you plan to attend the TEP Unitholder Meeting and wish to vote in person, you will be given a ballot at the TEP Unitholder Meeting.

By order of the Board of Directors of Tallgrass MLP GP, LLC, as the general partner of Tallgrass Energy Partners, LP.

David G. Dehaemers, Jr.

President and Chief Executive Officer

Tallgrass MLP GP, LLC

IMPORTANT NOTE ABOUT THIS PROXY STATEMENT/PROSPECTUS

This proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the Securities and Exchange Commission, which is referred to as the “SEC” or the “Commission,” constitutes a proxy statement of TEP under Section 14(a) of the Securities Exchange Act of 1934, as amended, which is referred to as the “Exchange Act,” with respect to the solicitation of proxies for the special meeting of the TEP Unitholders to, among other things, approve the Merger Agreement and the Transactions. This proxy statement/prospectus is also a prospectus of TEGP under the Securities Act of 1933, as amended, which is referred to as the “Securities Act,” for TEGP Class A Shares that will be issued to holders of TEP Public Units in the Transactions pursuant to the Merger Agreement.

As permitted under the rules of the SEC, this proxy statement/prospectus incorporates by reference important business and financial information about TEGP and TEP from other documents filed with the SEC that are not included in or delivered with this proxy statement/prospectus. Please read “Where You Can Find More Information” beginning on page 141. You can obtain any of the documents incorporated by reference into this document from the SEC’s website at http://www.sec.gov. This information is also available to you without charge upon your request in writing or by telephone from TEGP or TEP, as the case may be, at the following addresses and telephone numbers:

Please note that copies of the documents provided to you will not include exhibits, unless the exhibits are specifically incorporated by reference into the documents or this proxy statement/prospectus.

You may obtain certain of these documents at TEGP’s website, www.tallgrassenergy.com, by selecting “Investors,” then selecting “Tallgrass Energy GP, LP,” then selecting “SEC Filings,” and then selecting “Documents,” and at TEP’s website, www.tallgrassenergy.com, by selecting “Investors,” then selecting “Tallgrass Energy Partners, LP,” then selecting “SEC Filings,” and then selecting “Documents.” Information contained on TEP’s and TEGP’s websites is expressly not incorporated by reference into this proxy statement/prospectus.

In order to receive timely delivery of requested documents in advance of the TEP Unitholder Meeting, your request should be received no later than June 18, 2018. If you request any documents, TEGP or TEP, as applicable, will mail them to you by first class mail, or another equally prompt means, after receipt of your request.

TEGP and TEP have not authorized anyone to give any information or make any representation about the Transactions, TEGP or TEP that is different from, or in addition to, that contained in this proxy statement/prospectus or in any of the materials that have been incorporated by reference into this proxy statement/prospectus. Therefore, if anyone distributes this type of information, you should not rely on it. If you are in a jurisdiction where offers to exchange or sell, or solicitations of offers to exchange or purchase, the securities offered by this proxy statement/prospectus or the solicitation of proxies is unlawful, or you are a person to whom it is unlawful to direct these types of activities, then the offer presented in this proxy statement/prospectus does not extend to you. The information contained in this proxy statement/prospectus speaks only as of the date of this proxy statement/prospectus, or in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies. All information in this document concerning TEGP has been furnished by TEGP. All information in this document concerning TEP has been furnished by TEP. TEGP has represented to TEP, and TEP has represented to TEGP, that the information furnished by and concerning it is true and correct in all material respects.

TABLE OF CONTENTS

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ANNEXES

ii

DEFINITIONS

The following terms have the meanings set forth below for purposes of this proxy statement/prospectus, unless the context otherwise indicates:

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QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE TEP UNITHOLDER MEETING

Important Information and Risks. The following are brief answers to some questions that you may have regarding the Merger Proposal and the TEP Unitholder Meeting. You should read and consider carefully the remainder of this proxy statement/prospectus, including the “Risk Factors” beginning on page 22 and the attached Annexes, because the information in this section does not provide all of the information that might be important to you. Additional important information and descriptions of risk factors are also contained in the documents incorporated by reference into this proxy statement/prospectus. Please read “Where You Can Find More Information” beginning on page 141.

On March 26, 2018, TEGP, TE, Merger Sub, TEP, and TEP GP entered into the Merger Agreement. Pursuant to the Merger Agreement, Merger Sub will merge with and into TEP, with TEP surviving the Merger as a wholly owned subsidiary of TE and its subsidiaries. At the Effective Time, each issued and outstanding TEP Public Unit, will be converted into the right to receive 2.0 TEGP Class A Shares. No fractional TEGP Class A Shares will be issued in connection with the Merger. All fractional TEGP Class A Shares that a holder of TEP Public Units would otherwise be entitled to receive as merger consideration (after taking into account all TEP Public Units held by such holder) will be aggregated and then, if a fractional TEGP Class A Share results from that aggregation, be rounded up to the nearest whole TEGP Class A Share.

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Current TEGP Shareholders will continue to receive distributions on their TEGP Class A Shares in accordance with the TEGP Partnership Agreement and at the discretion of the TEGP GP Board. For a description of the distribution provisions of TEGP’s Partnership Agreement, please read “Comparison of the Rights of TEP Unitholders and TEGP Shareholders.”

The current annualized distribution rate for each TEP Common Unit is $3.90 (based on the quarterly distribution rate of $0.975 for each TEP Common Unit to be paid on May 15, 2018 with respect to the first quarter of 2018). Based on the Exchange Ratio, the annualized distribution rate for each TEP Common Unit exchanged for 2.0 TEGP Class A Shares would be approximately $3.90 (based on the quarterly distribution rate of $0.4875 per TEGP Class A Share to be paid on May 15, 2018 with respect to the first quarter of 2018).

The TEP GP Board, based in part upon the recommendation of the TEP Conflicts Committee, unanimously determined that the Merger Agreement and the Transactions are in the best interests of TEP and the TEP Unitholders, approved the Merger Agreement and the Transactions, directed that the Merger Agreement and the Transactions be submitted to a vote of the TEP Unitholders at a meeting in accordance with the TEP Partnership Agreement, and determined to recommend that the TEP Unitholders approve the Merger Agreement and the Transactions.

Accordingly, each of the TEP Conflicts Committee and the TEP GP Board recommends that the TEP Unitholders vote “FOR” the Merger Proposal.

For additional information, see “The Merger—Reasons for the TEP Conflicts Committee’s Recommendation”

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Proxies received but marked as abstentions will be counted as units that are present and entitled to vote for purposes of determining the presence of a quorum. A broker non-vote will also be considered present at the meeting for purposes of determining the presence of a quorum but cannot be included in the vote. Abstentions and broker non-votes have the same effect as a vote against the Merger for purposes of the vote required under the Merger Agreement and the TEP Partnership Agreement.

For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

If you own TEP Common Units that are directly registered in your name with the transfer agent and return a signed proxy card or submit your proxy via the Internet or by telephone but do not indicate how you wish your TEP Common Units to be voted, TEP Common Units represented by your properly submitted proxy card will be voted “FOR” the Merger Proposal.

For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

If your TEP Common Units are held through a bank, broker or other nominee, you should follow the instructions of your bank, broker or other nominee regarding the revocation of proxies. If your bank, broker or other nominee allows you to submit your proxy via telephone or Internet, you may be able to change your proxy by submitting a proxy again by telephone or Internet.

For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

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For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

Contemporaneously with the execution and delivery of the Merger Agreement, TEGP and TE entered into the Support Agreement with TEP, pursuant to which, TE agreed to, and TEGP agreed to cause TE to, among other things and while the Support Agreement remains in effect, vote the 25,619,218 TEP Common Units (representing approximately 35.0% of the outstanding TEP Common Units) held of record and beneficially by TE in favor of the approval of the Merger Agreement and the Transactions at any meeting of the TEP Unitholders.

For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

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For additional information, see “Information about the TEP Unitholder Meeting and Voting.”

Proxies also may be solicited by TEP GP’s and its affiliates’ directors, officers and employees by telephone, electronic mail, letter, facsimile or in person, but no additional compensation will be paid to them.

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For additional information, please see “The Merger Agreement—Conditions to the Merger.”

Please read “Material U.S. Federal Income Tax Consequences” for a more complete discussion of the expected material U.S. federal income tax consequences of the Merger.

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Please read “Material U.S. Federal Income Tax Consequences” for a more complete discussion of the expected material U.S. federal income tax consequences of owning and disposing of TEGP Class A Shares received in the Merger.

Banks, brokers and other nominees may be participating in the practice of “householding” proxy statements and annual reports. As indicated in the notice provided by these banks, brokers and other nominees to TEP Unitholders, a single proxy statement will be delivered to multiple TEP Unitholders sharing an address unless contrary instructions have been received from an affected TEP Unitholder. Once you have received notice from your bank, broker or other nominee that it will be “householding” communications to your address, “householding” will continue until you are notified otherwise or until you revoke your consent. If, at any time, you would prefer to receive separate copies of the proxy statement either now or in the future, please contact your bank, broker or other nominee or contact MacKenzie Partners, Inc., TEP’s proxy solicitor, or contact TEP by written or oral request to TEP at the address and telephone number stated above.

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RISK FACTORS

You should consider carefully the following risk factors, together with all of the other information included in, or incorporated by reference into, this proxy statement/prospectus before deciding how to vote. In particular, please read Part I, Item 1A, “Risk Factors,” in the Annual Reports on Form 10-K for the year ended December 31, 2017 for each of TEGP and TEP incorporated by reference herein. This document also contains forward-looking statements that involve risks and uncertainties. Please read “Cautionary Statement Regarding Forward-Looking Statements.”

Risks Related to the Merger

The number of TEGP Class A Shares that holders of TEP Public Units will be entitled to receive in the Merger is based upon the Exchange Ratio, which is a fixed exchange ratio. As a result, the market value of the TEGP Class A Shares that holders of TEP Public Units receive for their TEP Public Units in the Merger could decrease prior to the consummation of the Merger.

The Exchange Ratio is fixed, meaning that it will not change prior to closing of the Transactions. There is no “price protection” mechanism contained in the Merger Agreement that adjusts the number of TEGP Class A Shares that holders of TEP Public Units will receive based on any decreases in the trading price of TEGP Class A Shares or increases in the trading price of TEP Common Units. As a result, holders of TEP Public Units may receive less value for their TEP Public Units than the value calculated pursuant to the Exchange Ratio on the date the Merger Agreement was executed. For example, if the price of TEGP Class A Shares decreases prior to closing for any reason and the trading price of the TEP Common Units remains the same, the value received by holders of TEP Public Units in the Merger will decrease. Holders of TEP Public Units will also receive less value in the Merger if the trading price for the TEP Common Units increases prior to closing and the trading price TEGP for TEGP Class A Shares remains the same. This potential diminution in value received by holders of TEP Public Units in the Merger could be substantial. For historical and current market prices of TEGP Class A Shares and TEP Common Units, please read the “Market Price and Cash Distribution Information” section of this proxy statement/prospectus.

The U.S. federal income tax liability of a holder of TEP Public Units as a result of the Merger could be more than expected.

As a result of the Merger, a holder of TEP Public Units that is a U.S. holder (as defined in “Material U.S. Federal Income Tax Consequences”) will recognize gain or loss for U.S. federal income tax purposes equal to the difference between (i) the sum of (A) the fair market value of the TEGP Class A Shares received and (B) such holder’s share of TEP’s nonrecourse liabilities immediately prior to the Merger, and (ii) the holder’s adjusted tax basis in the TEP Public Units exchanged therefor (which includes such holder’s share of TEP’s nonrecourse liabilities immediately prior to the Merger). Because the fair market value of any TEGP Class A Shares received in the Merger will not be known until the Effective Time of the Merger, such holder of TEP Public Units will not be able to determine its amount realized, and therefore its taxable gain or loss, until such time. In addition, because prior distributions from TEP in excess of such holder’s allocable share of TEP’s net taxable income decrease such holder’s tax basis in its TEP Public Units, the amount, if any, of such prior excess distributions with respect to such TEP Common Units will, in effect, become taxable income to such holder of TEP Public Units if the aggregate fair market value of the TEGP Class A Shares received in the Merger is greater than such holder’s adjusted tax basis in its TEP Public Units, even if the aggregate fair market value of the TEGP Class A Shares received in the Merger is less than such holder’s original cost basis in its TEP Public Units. Furthermore, a portion of this gain or loss, which could be substantial, will be separately computed and taxed as ordinary income or loss to the extent attributable to “unrealized receivables,” including depreciation recapture, or to “inventory items” owned by TEP and its subsidiaries.

For a more complete discussion of certain U.S. federal income tax consequences of the Merger, please read “Material U.S. Federal Income Tax Consequences.”

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Holders of TEP Public Units will receive no cash consideration with which to pay any potential U.S. federal income tax liability resulting from the Merger.

Holders of TEP Public Units will receive no cash consideration in the Merger. Yet the receipt of TEGP Class A Shares in exchange for TEP Public Units in the Merger will be treated as a taxable sale by such holders that are U.S. holders (as defined in “Material U.S. Federal Income Tax Consequences”) of such common units for U.S. federal income tax purposes. The amount of gain or loss recognized by each such holder of TEP Public Units in the Merger will vary depending on such holder’s particular situation, including the fair market value of the TEGP Class A Shares received by such holder in the Merger, the adjusted tax basis of the TEP Public Units exchanged by such holder in the Merger and the amount of any suspended passive losses that may be available to such holder to offset a portion of the gain recognized by such holder.

For a more complete discussion of certain U.S. federal income tax consequences of the Merger, please read “Material U.S. Federal Income Tax Consequences.”

TEP is subject to provisions that limit its ability to pursue alternatives to the Merger, could discourage a potential competing acquirer of TEP from making a favorable alternative transaction proposal and, in specified circumstances under the Merger Agreement, could require TEP to pay certain transaction expenses of TEGP.

Under the Merger Agreement, TEP is restricted from entering into alternative transactions. Unless and until the Merger Agreement is terminated, subject to specified exceptions (which are discussed in more detail in “The Merger Agreement—Acquisition Proposals; Adverse Recommendation Changes”), TEP GP, for and on behalf of TEP and its subsidiaries, will not, and will use their respective reasonable best efforts to cause their respective representatives not to, directly or indirectly, initiate, solicit or knowingly encourage or facilitate the submission of any acquisition proposal. Under the Merger Agreement, in the event of a potential change by the TEP Conflicts Committee or the TEP GP Board of its recommendation with respect to the Merger in light of a superior proposal or an intervening event, TEP GP must cause such information to be presented to the TEGP GP Board orally and in writing as promptly as practicable (and in any event within 24 hours of receipt) to allow TEGP to propose an adjustment to the terms and conditions of the Merger Agreement. These provisions could discourage a third party that may have an interest in acquiring all or a significant part of TEP from considering or proposing that acquisition, even if such third party were prepared to pay consideration with a higher per unit market value than the market value of the consideration proposed to be received or realized in the merger, or might result in a potential competing acquirer of TEP proposing to pay a lower price than it would otherwise have proposed to pay because of the added expense of the TEGP transaction fees that may become payable in specified circumstances.

Under the Merger Agreement, TEP may be required to pay TEGP’s transaction expenses if the Merger Agreement is terminated by TEGP under specified circumstances (which are discussed in more detail in “The Merger Agreement—Termination”).

For a discussion of the restrictions on TEP soliciting or entering into a takeover proposal or alternative transaction and the TEP Conflicts Committee’s or the TEP GP Board’s ability to change their recommendation, see “The Merger Agreement—Acquisition Proposals; Adverse Recommendation Changes.”

TEP may, under certain specified circumstances, be responsible for TEGP’s expenses in an amount up to $3 million.

If the Merger Agreement is terminated by TEGP (i) in connection with a TEP adverse recommendation change (as defined below in “The Merger Agreement—Covenants—Acquisition Proposals; TEP Adverse Recommendation Changes”), or (ii) due to a material breach by TEP of its representations, warranties, covenants or agreements under the Merger Agreement, TEP will reimburse to TE, on behalf of TEGP, certain expenses of

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the members of the TEGP Group (other than, with respect to TEP GP, the TEP Conflicts Committee) and TEGP GP not exceeding $3 million. See “The Merger Agreement—Termination—Termination Rights” and “The Merger Agreement—Termination—Termination Expenses.” If such expenses are payable, the payment of such expenses could potentially negatively impact the financial condition and operations of TEP.

The Merger may not be consummated even if the TEP Unitholders approve the Merger Proposal, which may cause the market price of TEP Common Units to decline.

The Merger Agreement contains conditions, some of which are beyond the parties’ control, such as any required regulatory approvals, that, if not satisfied or waived, may prevent, delay or otherwise result in the Merger not occurring, even though TEP Unitholders may have voted to approve the Merger Proposal. TEGP and TEP cannot predict with certainty whether and when any of the conditions to the completion of the Merger will be satisfied. Any delay in completing the Merger could cause TEGP not to realize, or delay the realization of, some or all of the benefits that TEGP expects to achieve from the Merger. In addition, TEGP and TEP can agree not to consummate the Merger even if the TEP Unitholders approve the Merger Proposal and the conditions to the closing of the Merger are otherwise satisfied. If the Merger does not occur, the market price of TEP Common Units may decline.

If the Merger does not occur, TEP will not benefit from the expenses it has incurred in the pursuit of the Merger.

The Merger may not be completed. If the Merger is not completed, TEP will have incurred substantial expenses for which no ultimate benefit will have been received by it. TEP currently expects to incur merger-related expenses of approximately $3.0 million, consisting of independent advisory, legal and accounting fees, and financial printing and other related charges, much of which may be incurred even if the Merger is not completed. In addition, if the Merger Agreement is terminated under specified circumstances, TEP will be required to pay certain expenses of TEGP. See “The Merger Agreement—Termination Expenses.”

Financial projections by TEGP and TEP may not prove accurate.

In performing its financial analyses and rendering its fairness opinion, the financial advisor to the TEP Conflicts Committee reviewed and relied on, among other things, internal financial analyses and forecasts for TEP and TEGP, which were prepared by employees of Tallgrass Management, including those who normally render services to TEP. These financial projections include assumptions regarding future operating cash flows, capital expenditures and associated funding of TEP and TEGP. These financial projections were not prepared with a view to public disclosure, are subject to significant economic, competitive, industry and other uncertainties, and may not be achieved in full, at all, or within projected timeframes. The failure of TEP’s or TEGP’s businesses to achieve projected results, including projected cash flows, could have a material adverse effect on the price of TEGP Class A Shares, TEGP’s financial position and TEGP’s ability to maintain or increase its dividends following the Merger.

The fairness opinion rendered to the TEP Conflicts Committee by its financial advisor was based on the financial analysis performed by the financial advisor, which considered factors such as market and other conditions then in effect, and financial forecasts and other information made available to the financial advisor, as of the date of its opinion. As a result, this opinion does not reflect changes in events or circumstances after the date of the opinion. The TEP Conflicts Committee has not obtained, and does not expect to obtain, an updated fairness opinion from its financial advisor reflecting changes in circumstances that may have occurred since the signing of the Merger Agreement.

The fairness opinion rendered to the TEP Conflicts Committee by Evercore was provided in connection with, and at the time of, the TEP Conflicts Committee’s evaluation of the Merger and the Merger Agreement. This opinion was based on the financial analysis performed, which considered market and other conditions then

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in effect, and financial forecasts and other information made available to Evercore, as of the date of its opinion, which may have changed, or may change, after the date of the opinion. The TEP Conflicts Committee has not obtained an updated opinion as of the date of this proxy statement/prospectus from its financial advisor, and it does not expect to obtain an updated opinion prior to completion of the Merger. Changes in the operations and prospects of TEGP or TEP, general market and economic conditions and other factors which may be beyond the control of TEGP and TEP, and on which the fairness opinion was based, may have altered the value of TEGP or TEP or the prices of TEGP Class A Shares or TEP Common Units since the date of such opinion, or may alter such values and prices by the time the Merger is completed. The opinion does not speak as of any date other than the date of the opinion. For a description of the opinion that the TEP Conflicts Committee received from its financial advisor, please refer to “Opinion of Evercore—Financial Advisor to the TEP Conflicts Committee.”

TEGP GP, TEP GP and their officers and directors may have interests that differ in certain respects from those of the TEP Unitholders, and these interests may have influenced their decision to propose and to approve the Merger Agreement and the Transactions.

In considering the recommendation of the TEP GP Board and the TEP Conflicts Committee with respect to the Merger Proposal, the TEP Unitholders should be aware that certain Exchange Right Holders and certain of the executive officers and directors of TEP GP have interests in the transaction that differ from, or are in addition to, the interests of the TEP Unitholders generally, including:

See “The Merger—Certain Relationships; Interests of Certain Persons in the Merger.

If the Merger Proposal is approved by TEP Unitholders, the date that those unitholders will receive the Merger Consideration is uncertain.

As described in this proxy statement/prospectus, completion of the Merger is subject to a number of conditions, not all of which are controllable or waivable by TEGP or TEP. Accordingly, if the Merger Proposal is approved by TEP Unitholders, the date that those unitholders will receive the Merger Consideration depends on the completion date of the Merger, which is uncertain.

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Lawsuits have been filed against TEP and the directors of TEP GP challenging the Merger, and any injunctive relief or adverse judgment for monetary damages could prevent the Merger from occurring or could have a material adverse effect on TEGP following the Merger.

TEP and the directors of TEP GP are named defendants in a purported class action brought by a TEP Unitholder in the United States District Court for the District of Delaware, challenging under the federal securities laws the accuracy of the disclosures made in the registration statement on Form S-4 regarding the Merger. A second lawsuit with substantially the same allegations has been filed by a different TEP Unitholder in the United States District Court for the District of Delaware against the same defendants. Both plaintiffs seek to enjoin the defendants from proceeding with or consummating the Merger and, to the extent that the Merger is implemented before relief is granted, the plaintiff in the second lawsuit seeks to have the Merger rescinded. Both plaintiffs also seek money damages and an award of costs and attorneys’ and experts’ fees. One of the conditions to the completion of the Merger is that no order, decree or injunction of any court or agency of competent jurisdiction shall be in effect, and no law shall have been enacted or adopted, that enjoins, prohibits or makes illegal consummation of any of the Transactions. A preliminary injunction could delay or jeopardize the completion of the Merger, and an adverse judgment granting permanent injunctive relief could indefinitely enjoin completion of the Merger. An adverse judgment for rescission or for monetary damages could have a material adverse effect on TEGP following the Merger.

Risks Related to the Ownership of TEGP Class A Shares

TEGP’s future tax liability and the portion of distributions paid to you treated as taxable dividend income may be greater than expected.

TEGP expects that available deductions will offset its taxable income so that it will not pay U.S. federal income tax in any of the taxable periods ending December 31, 2018, through December 31, 2027, and that during this period no more than 20% of the distributions paid by TEGP to you should be treated as taxable dividend income under current U.S. federal tax regulations, with the remaining distributions treated as a return of capital. These estimates are based on assumptions with respect to, among other things, income, capital expenditures, net working capital, TEP’s and TE’s earnings from operations, the amount of those earnings allocated to TEGP, TEGP’s income tax liabilities, the amount of distributions paid to TEGP by TE, the amount and availability of depreciation deductions allocable to TEGP, valuations of TEP, TE and TEGP, and the effects on TEP, TE and TEGP of the recently enacted tax legislation known as the Tax Cuts and Jobs Act of 2017. Further, these estimates are based on current tax law and tax reporting positions that TEGP, TEP and TE will adopt and with which the IRS could disagree. Accordingly, we cannot assure you that these estimates will prove to be correct.

For a more complete discussion of certain U.S. federal income tax consequences of owning and disposing of TEGP Class A Shares, please read “Material U.S. Federal Income Tax Consequences.”

We expect that TEGP’s ability to use net operating losses arising prior to the Merger to offset future income will be limited as a result of the Merger, and its ability to use net operating losses arising after the Merger to offset future income may be limited.

We expect that TEGP’s ability to use any net operating losses (“NOLs”) generated by it prior to the Merger to offset future income will be limited due to experiencing an “ownership change” as defined under Section 382 of the Code as a result of the Merger. TEGP’s ability to use NOLs arising after the Merger to offset future income may be substantially limited if it were to experience another ownership change.

In general, an ownership change occurs if TEGP’s “5-percent shareholders,” as defined under Section 382 of the Code, including certain groups of persons treated as 5-percent shareholders, collectively increased their ownership in TEGP’s Class A Shares by more than 50 percentage points over a rolling three-year period. An ownership change can occur as a result of a public offering of TEGP’s Class A Shares, as well as through secondary market purchases of TEGP’s Class A Shares and certain types of reorganization transactions. As a result of the exchange of TEP Common Units for TEGP Class A Shares in the Merger, we expect that the Merger will cause TEGP to experience an ownership change.

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A corporation (including any entity such as TEGP that is treated as a corporation for U.S. federal income tax purposes) that experiences an ownership change will generally be subject to an annual limitation on the use of its pre-ownership change NOLs (and certain other losses and credits) equal to the equity value of the corporation immediately before the ownership change, multiplied by the long-term tax-exempt rate (as determined by the Internal Revenue Service) for the month in which the ownership change occurs. Such a limitation could, for any given year, have the effect of increasing the amount of TEGP’s U.S. federal income tax liability, which would negatively impact the amount of after-tax cash available for distribution to holders of TEGP’s Class A Shares and TEGP’s financial condition.

For a more complete discussion of certain U.S. federal income tax consequences of owning and disposing of TEGP Class A Shares, please read “Material U.S. Federal Income Tax Consequences.”

TEGP’s distributions to the TEGP Shareholders are not cumulative.

TEGP’s distributions to the TEGP Shareholders are not cumulative. Consequently, if distributions on TEGP Class A Shares are not paid with respect to any fiscal quarter, then TEGP Shareholders will not be entitled to receive that quarter’s payments in the future.

TEGP Shareholders do not vote in the election of TEGP GP’s directors. The Exchange Right Holders own a sufficient number of shares to allow them to prevent the removal of TEGP GP.

TEGP Shareholders have only limited voting rights on matters affecting TEGP’s business and, therefore, limited ability to influence management’s decisions regarding TEGP’s business. The TEGP GP Board, including its independent directors, is designated and elected by Holdings or its designees. TEGP Shareholders do not have the ability to elect the members of the TEGP GP Board.

In addition, if TEGP Shareholders are dissatisfied with the performance of TEGP GP, they have little ability to remove TEGP GP. TEGP GP may not be removed except by vote of the holders of at least 80% of our outstanding shares, voting together as a single class. The Exchange Right Holders own approximately 68.57% of TEGP’s outstanding shares as of May 2, 2018 and will own approximately 45.26% of TEGP’s outstanding shares following the Merger, not taking into account any TEP EPUs or TEGP EPSs that may vest prior to the consummation of the Merger. This ownership level enables the Exchange Right Holders to prevent TEGP GP’s removal.

As a result of these provisions, the price at which TEGP’s Class A Shares trade may be lower because of the absence or reduction of a takeover premium in the trading price.

The TEGP Partnership Agreement restricts the rights of TEGP Shareholders owning 20% or more of TEGP’s shares.

TEGP Shareholders’ voting rights are restricted by the provision in the TEGP Partnership Agreement generally providing that any shares held by a person or group that owns 20% or more of any class of shares then outstanding, other than TEGP GP, the Exchange Right Holders or their respective affiliates and persons who acquired such shares with the prior approval of the TEGP GP Board, cannot be voted on any matter. In addition, the TEGP Partnership Agreement contains provisions limiting the ability of TEGP Shareholders to call meetings or to acquire information about TEGP’s operations, as well as other provisions limiting TEGP Shareholders’ ability to influence the manner or direction of TEGP’s management. As a result, the price at which the TEGP Class A Shares trade may be lower because of the absence or reduction of a takeover premium in the trading price.

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Future sales of TEGP Class A Shares in the public market, including sales of TEGP Class A Shares by the Exchange Right Holders after the exercise of the Exchange Right, could reduce the TEGP Class A Share price, and any additional capital raised by TEGP through the sale of equity or convertible securities may dilute your ownership in TEGP.

Subject to certain limitations and exceptions, the Exchange Right Holders may cause the exchange of their TE Units (together with a corresponding number of TEGP Class B Shares) for TEGP Class A Shares (on a one-for-one basis, subject to customary conversion rate adjustments for equity splits and reclassification and other similar transactions) and then sell those TEGP Class A Shares. Pursuant to a shareholder and registration rights agreement entered into with the Exchange Right Holders, TEGP has registered the resale of 109,504,440 TEGP Class A Shares issuable upon exercise of the Exchange Right pursuant to TEGP’s Form S-3/A (File No. 333-210976) filed with the SEC on August 8, 2016, which became effective August 10, 2016. Following such registration, certain participating Exchange Right Holders sold 10,350,000 TEGP Class A Shares in a secondary offering that closed on November 22, 2016. TEGP currently intends to register the 27,554,785 TEGP Class A Shares issuable upon the exercise of the Exchange Right with respect to the 27,554,785 units and TEGP Class B Shares, respectively, issued in connection with the acquisition of the 25.01% membership interest in Rockies Express and the 5,619,218 TEP Common Units acquired by TE on February 7, 2018. TEGP will likely issue additional TEGP Class A Shares or convertible securities in subsequent public or private offerings.

TEGP cannot predict the size of future issuances of TEGP Class A Shares or securities convertible into TEGP Class A Shares or the effect, if any, that future issuances and sales of TEGP Class A Shares, including sales of TEGP Class A Shares by the Exchange Right Holders after the exercise of the Exchange Right, will have on the market price of TEGP Class A Shares. Sales of substantial amounts of TEGP Class A Shares (including shares issued in connection with an acquisition), or the perception that such sales could occur, may adversely affect prevailing market prices of TEGP Class A Shares.

TEGP GP may cause TEGP to issue additional TEGP Class A Shares or other equity securities, including equity securities that are senior to the TEGP Class A Shares, without your approval, which may adversely affect you.

TEGP GP may cause TEGP to issue an unlimited number of additional TEGP Class A Shares, or other equity securities of equal rank with the TEGP Class A Shares, without shareholder approval. In addition, TEGP may issue an unlimited number of shares that are senior to TEGP Class A Shares in right of distribution, liquidation and voting. Except for TEGP Class A Shares issued in connection with the exercise by any Exchange Right Holder of its right to exchange a TEGP Class B Share for a TEGP Class A Share, each of which will result in the cancellation of an equivalent number of TEGP Class B Shares and therefore have no effect on the total number of outstanding shares, the issuance of additional TEGP Class A Shares, or other equity securities of equal or senior rank, may have the following effects:

The TEGP Partnership Agreement eliminates TEGP GP’s fiduciary duties to holders of TEGP Class A Shares and replaces them with contractual standards governing its conduct.

The TEGP Partnership Agreement contains provisions that eliminate the fiduciary standards to which its general partner would otherwise be held by state fiduciary duty law and replaces those duties with several

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different contractual standards. For example, the TEGP Partnership Agreement permits TEGP GP to make a number of decisions in its individual capacity, as opposed to in its capacity as TEGP’s general partner, free of any duties to TEGP and its shareholders other than the implied contractual covenant of good faith and fair dealing, which means that a court will enforce the reasonable expectations of the shareholders where the language in the partnership agreement does not provide for a clear course of action. This provision entitles TEGP GP to consider only the interests and factors that it desires and relieves it of any duty or obligation to give any consideration to any interest of, or factors affecting, TEGP, its affiliates or its shareholders. Examples of decisions that TEGP GP may make in its individual capacity include:

In addition, the TEGP Partnership Agreement provides that any construction or interpretation of its partnership agreement and any action taken pursuant thereto or any determination, in each case, made by TEGP GP in good faith, shall be conclusive and binding on all shareholders.

By acquiring TEGP Class A Shares in the Merger, you will be bound by the provisions in the TEGP Partnership Agreement, including the provisions discussed above.

The contractual standards for TEGP GP’s conduct set forth in the TEGP Partnership Agreement restrict the remedies available to holders of TEGP Class A Shares for actions taken by TEGP GP that might otherwise constitute breaches of fiduciary duty.

The TEGP Partnership Agreement contains contractual standards for TEGP GP’s conduct that restrict the remedies available to shareholders for actions taken by TEGP GP that might otherwise constitute breaches of fiduciary duty under state fiduciary duty law. For example, the TEGP Partnership Agreement provides that:

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In connection with a situation involving a transaction with an affiliate or a conflict of interest, any determination by TEGP GP or the conflicts committee must be made in good faith. If an affiliate transaction or the resolution of a conflict of interest is not approved by TEGP’s shareholders or the conflicts committee and the board of directors of TEGP GP determines that the resolution or course of action taken with respect to the affiliate transaction or conflict of interest satisfies either of the standards set forth in the last two bullets above, then it will be presumed that, in making its decision, the board of directors acted in good faith, and in any proceeding brought by or on behalf of any limited partner or the partnership challenging such determination, the person bringing or prosecuting such proceeding will have the burden of overcoming such presumption.

TEGP GP has a call right that may require you to sell your TEGP Class A Shares at an undesirable time or price.

If at any time more than 80% of TEGP’s outstanding shares (including TEGP Class A Shares issuable upon the exchange of TEGP Class B Shares) are owned by TEGP GP, Holdings or their respective affiliates, TEGP GP has the right (which it may assign to any of its affiliates, Holdings or TEGP), but not the obligation, to acquire all, but not less than all, of the remaining TEGP Class A Shares held by public shareholders at a price equal to the greater of (x) the highest cash price paid by TEGP GP, Holdings, or their respective affiliates for any shares purchased within the 90 days preceding the date on which TEGP GP first mails notice of its election to purchase those shares and (y) the current market price calculated in accordance with the TEGP Partnership Agreement as of the date three business days before the date the notice is mailed. As a result, you may be required to sell your TEGP Class A Shares at an undesirable time or price and may not receive any return of or on your investment. You may also incur a tax liability upon a sale of your TEGP Class A Shares.

The U.S. federal income tax treatment of owning and disposing of TEGP Class A Shares received in the Merger will be different than the U.S. federal income tax treatment of owning and disposing of TEP Common Units.

TEP is classified as a partnership for U.S. federal income tax purposes and, generally, is not subject to entity-level U.S. federal income taxes. Instead, each TEP Unitholder is required to take into account its respective share of TEP’s items of income, gain, loss and deduction in computing its U.S. federal income tax liability as if the unitholder had earned such income directly, even if no cash distributions are made to the TEP Unitholder. A pro rata distribution of cash by TEP to a TEP Unitholder who is a U.S. holder (as defined in “Material U.S. Federal Income Tax Consequences”) is generally not taxable for U.S. federal income tax purposes unless the amount of cash distributed is in excess of the holder’s adjusted tax basis in its TEP Common Units.

In contrast, TEGP is classified as a corporation for U.S. federal income tax purposes and is subject to U.S. federal income tax on its taxable income. A distribution by TEGP to a TEGP Shareholder who is a U.S. holder

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generally will be included in such U.S. holder’s income as ordinary dividend income to the extent of TEGP’s current or accumulated “earnings and profits,” as determined under U.S. federal income tax principles. A portion of the distributions to TEGP Shareholders by TEGP after the Merger may exceed TEGP’s current and accumulated earnings and profits. Distributions in excess of TEGP’s current and accumulated earnings and profits will be treated as a non-taxable return of capital, reducing a U.S. holder’s adjusted tax basis in such TEGP Shareholder’s TEGP Class A Shares and, to the extent the distribution exceeds such TEGP Shareholder’s adjusted tax basis, as gain from the sale or exchange of such TEGP Class A Shares.

Please read “Material U.S. Federal Income Tax Consequences” for a more complete discussion of the expected material U.S. federal income tax consequences of owning and disposing of TEGP Class A Shares received in the Merger.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This proxy statement/prospectus and the documents TEGP and TEP have incorporated herein by reference contain forward-looking statements and information that reflects TEGP’s and/or TEP’s current expectations, certain projections of results of operations or of financial condition, or forecasts of future events. Words such as “could,” “will,” “may,” “assume,” “forecast, “position,” “predict,” “strategy,” “expect,” “intend,” “plan,” “estimate,” “anticipate,” “believe,” “project,” “budget,” “potential,” or “continue,” and similar expressions are used to identify forward-looking statements. Without limiting the generality of the foregoing, forward-looking statements contained in this proxy statement/prospectus include TEGP and TEP’s expectations of plans, strategies, objectives, growth and anticipated financial and operational performance, including guidance regarding TEGP’s infrastructure programs, revenue projections, capital expenditures and tax position. Forward-looking statements can be affected by assumptions used or by known or unknown risks or uncertainties. Consequently, no forward-looking statements can be guaranteed.

All statements other than statements of historical fact included or incorporated by reference in this proxy statement/prospectus, including statements regarding TEGP’s and/or TEP’s financial position, business strategy and other plans and objectives for future operations or transactions, and including statements regarding the approval of the Merger Agreement and the Transactions, the satisfaction of the closing conditions to the Merger, the timing of the completion of the Merger, expected U.S. federal income tax consequences, expectations and intentions regarding outstanding litigation, expectations with respect to the synergies, costs and other anticipated effects of the Merger and expectations regarding TEP’s business and common units if the Merger does not occur, are forward-looking statements.

A forward-looking statement may include a statement of the assumptions or bases underlying the forward-looking statement. TEGP and TEP believe that they have chosen these assumptions or bases in good faith and that they are reasonable. However, when considering these forward-looking statements, you should keep in mind the risk factors and other cautionary statements in this proxy statement/prospectus. Actual results may vary materially. You are cautioned not to place undue reliance on any forward-looking statements. You should also understand that it is not possible to predict or identify all such factors and should not consider the following list to be a complete statement of all potential risks and uncertainties. Factors that could cause actual results to differ materially from the results contemplated by such forward-looking statements include:

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