UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

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T-Mobile US, Inc.

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Your Vote Counts! T-MOBILE US, INC. 2024 Annual Meeting of Stockholders Vote by 11:59 P.M. EDT June 11, 2024 T-MOBILE US, INC. ATTN: BROADY HODDER 12920 SE 38TH STREET BELLEVUE, WA 98006 V40093-P10792 You invested in T-MOBILE US, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the stockholder meeting to be held on June 12, 2024. Get informed before you vote View the Notice and Proxy Statement and Annual Report online OR if you want to receive a paper or e-mail copy of these documents or proxy materials for future stockholder meetings, you must request them. To make your request, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Please make the request as instructed above on or before May 29, 2024 to facilitate timely delivery. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com* Control # Smartphone users Vote Virtually at the Meeting Point your camera here and June 12, 2024 9:00 A.M. PDT vote without entering a control number The Annual Meeting will be held solely by means of remote communication, in a virtual only format. To attend the meeting online, please visit www.virtualshareholdermeeting.com/TMUS2024 and be sure to have the control number noted above. *You can also vote by mail or by telephone by requesting a paper copy of the materials, which will include a proxy card with instructions. V2.0

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the Annual Meeting. Please follow the instructions on the reverse side to vote on these important matters. Voting Items Board Recommends 1. Election of Directors Nominees: 01) André Almeida 08) Raphael Kübler 02) Marcelo Claure 09) Thorsten Langheim For 03) Srikant M. Datar 10) Dominique Leroy 04) Srinivasan Gopalan 11) Letitia A. Long 05) Timotheus Höttges 12) G. Michael Sievert 06) Christian P. Illek 13) Teresa A. Taylor 07) James J. Kavanaugh 14) Kelvin R. Westbrook 2. Ratification of the Appointment of Deloitte & Touche LLP as the Company’s Independent Registered Public Accounting For Firm for Fiscal Year 2024. NOTE: Consider any other business that is properly brought before the Annual Meeting or any continuation, adjournment or postponement of the Annual Meeting. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Delivery Settings”. V40094-P10792