UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. -)

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TETRA TECHNOLOGIES, INC.

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

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TETRA Logo VOTE C1234567890 000004 ENDORSEMENT_LINE SACKPACK MR A SAMPLE DESIGNATION (IF ANY) ADD 1 ADD 2 ADD 3 ADD 4 ADD 5 ADD 6 Online Go to www.envisionreports.com/TTI or scan the QR code — login details are located in the shaded bar below. Votes submitted electronically must be received by 1:00 a.m., Mountain Time, on May 26, 2021. Stockholder Meeting Notice 123456789012345 Important Notice Regarding the Availability of Proxy Materials for the TETRA Technologies, Inc. Stockholder Meeting to be Held on Wednesday, May 26, 2021 Under Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual stockholders’ meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on and location of the annual meeting are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The 2021 proxy statement and annual report to stockholders are available at: www.envisionreports.com/TTI Easy Online Access — View your proxy materials and vote. Step 1: Go to www.envisionreports.com/TTI. Step 2: Click on Cast Your Vote or Request Materials. Step 3: Follow the instructions on the screen to log in. Step 4: Make your selections as instructed on each screen for your delivery preferences. Step 5: Vote your shares. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials. Obtaining a Copy of the Proxy Materials – If you want to receive a copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. Please make your request as instructed on the reverse side on or before May 14, 2021 to facilitate timely delivery. 2NOT COY 03FUIA

Stockholder Meeting Notice TETRA Technologies, Inc.’s Annual Meeting of Stockholders will be held on Wednesday, May 26, 2021, at the TETRA Technologies Corporate Headquarters Building, 24955 Interstate 45 North, The Woodlands, Texas, at 11:00 a.m. Local Time. Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board of Directors recommends a vote FOR all nominees in Proposal 1 and FOR Proposals 2, 3 and 4. 1. To elect seven directors to serve one-year terms ending at the 2022 Annual Meeting of Stockholders, or until their successors have been duly elected or appointed. Nominees: 01) Mark E. Baldwin 02) Thomas R. Bates, Jr. 03) John F. Glick 04) Gina A. Luna 05) Brady M. Murphy 06) William D. Sullivan 07) Shawn D. Williams 2. To ratify and approve the appointment of Grant Thornton LLP as TETRA’s independent registered public accounting firm for the fiscal year ending December 31, 2021. 3. To approve, on advisory basis, the compensation the named executive officers of TETRA Technologies, Inc. 4. To approve TETRA’s First Amended and Restated 2018 Equity Incentive Plan. PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must vote online or request a paper copy of the proxy materials to receive a proxy card. If you wish to attend and vote at the meeting, please bring this notice with you. You may obtain directions to the location of the 2021 annual meeting by contacting our Investor Relations Department at 281-367-1983 or at the Investor Relations area of our website at www.tetratec.com. Here’s how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. Internet – Go to www.envisionreports.com/TTI. Click Cast Your Vote or Request Materials. —Phone – Call us free of charge at 1-866-641-4276. — Email– Send an email to investorvote@computershare.com with “Proxy Materials TETRA Technologies, Inc.” in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, all requests for a paper copy of proxy materials must be received by May 14, 2021.