UNITEDSTATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER
PURSUANT TO RULE 13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934

Date of Report: June 24, 2025

Commission File Number: 001-39570

TIM S.A.
(Exact name of Registrant as specified in its Charter)

JoãoCabral de Melo Neto Avenue, 850 – North Tower – 12^th floor
22775-057 Rio de Janeiro, RJ, Brazil
(Address of principal executive office)

Indicate by check mark whether the registrant files or willfile annual reports under cover of Form 20-F or Form 40-F.

Form20-F ☒ Form40-F ☐

Indicate by check mark if the registrant is submitting theForm 6-K in paper as permitted by Regulation S-T Rule 101(b)(1).

Yes ☐ No ☒

Indicate by check mark if the registrant is submitting theForm 6-K in paper as permitted by Regulation S-T Rule 101(b)(7).

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TIM S.A.

Publicly-held company

CNPJ/MF No. 02.421.421/0001-11

NIRE 33.300.324.631

NOTICE TO THE MARKET

CONTROLLING COMPANY’S 2^ndDEBENTURES ISSUANCE

TIM S.A. ("Company")(B3: TIMS3; NYSE: TIMB) hereby informs its shareholders and the market in general that its controlling company TIM BRASIL SERVIÇOSE PARTICIPAÇÕES S.A. ("Controlling Company" or "Issuer") approved at the ExtraordinaryShareholders' Meeting held on June 23, 2025 ("EGM"), its 2nd (second) issuance of simple, non-convertible debentures,without collateral, in up to two (2) series ("Debentures" and "Issue")", respectively), in thetotal amount of R$ 5 billion, with the first series of Debentures, a maturity of five (5) years ("First Series Debentures")and the second series of Debentures, a maturity of seven (7) years ("Second Series Debentures"), with the Issue intendedexclusively for professional investors.

The procedure for collecting investment intentionsfrom potential investors in the Debentures will be carried out, with the receipt of reserves by the financial institutions that are partof the securities distribution system, responsible for the distribution of the Debentures, in the absence of maximum or minimum values("Bookbuilding Procedure"), in order to determine (i) the existence of the First Series Debentures and the demandfor each series of the Debentures, as well as the number of Debentures to be allocated to each series of the Issue, according to the systemof communicating vessels; (ii) the minimum amount to be allocated to the Second Series Debentures, which shall be R$1,666,667,000.00(one billion, six hundred and sixty-six million, six hundred and sixty-seven thousand reais), equivalent to 1,666,667 (one million, sixhundred and sixty-six thousand, six hundred and sixty-seven) Debentures; and (iii) the final rate for the remuneration of the Debenturesof each series, corresponding to 100% (one hundred percent) of the DI rate, plus exponentially a spread (surcharge) equivalentto a percentage to be defined through the Bookbuilding Procedure, such percentage being limited to, at most, 0.80% per year (eighty hundredthspercent), for the Debentures of the First Series, and 0.95% (ninety-five hundredths percent) per year, for the Debentures of the SecondSeries.

The net proceeds obtained from the Issue willbe used for (i) the early redemption of all the debentures of the 1st issue of the Controlling Company; and (ii) the payment of extraordinarydividends by the Issuer and/or various corporate purposes, in accordance with the corporate purpose of the Controlling Company, withinthe scope of the management of its business.

All the characteristics of the Issuance aredescribed in the minutes of the EGM.

This press release is for information purposesonly, under the terms of the legislation in force, and should not be interpreted or considered, for all legal purposes and effects, asa material for the sale and/or disclosure of the Debentures.

In accordance with the applicable regulationsand in compliance with the rules of conduct set forth therein, additional information about the Controlling Company and the Issue willbe made available in due course on the Controlling Company's Investor Relations website (http://timbrasilpart.com.br/) and any informationabout the Company is made available in http://ri.tim.com.br/.

Rio de Janeiro, June 24, 2025.

TIM S.A.

Alberto Mario Griselli

Chief Executive Officer and

Investor Relations Officer

SIGNATURES

Pursuant to the requirements of theSecurities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereuntoduly authorized.