UNITED STATES
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: May 5, 2026

Commission File Number: 001-39570

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

João Cabral 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 will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

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

Yes ☐ No ☒

TIM S.A.

INDIVIDUAL AND CONSOLIDATED QUARTERLY INFORMATION

March 31, 2026

TIM S.A.

INDIVIDUAL AND CONSOLIDATED QUARTERLY INFORMATION

March 31, 2026

Contents

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

See the accompanying notes to the individual and consolidated quarterly information.

1.1. Corporate structure

TIM S.A. (“TIM” or “Company”) is a public limited company with Registered office in the city of Rio de Janeiro, RJ, and a subsidiary of TIM Brasil Serviços e Participações S.A. (“TIM Brasil”). TIM Brasil is a subsidiary of the Telecom Italia Group that holds 67.48% of the share capital of TIM S.A on March 31, 2026 (67.48% on December 31, 2025).

The Company holds an authorization for Landline Switched Telephone Service (“STFC”) in Local, National Long-Distance and International Long-Distance modes, as well as Personal Mobile Service (“SMP”) and Multimedia Communication Service (“SCM”), in all Brazilian states and in the Federal District.

The Company’s shares are traded on B3 – Brasil, Bolsa, Balcão (“B3”). Additionally, TIM has American Depositary Receipts (ADRs), Level II, traded on the New York Stock Exchange (NYSE) – USA. As a result, the company is subject to the rules of the Brazilian Securities and Exchange Commission (“CVM”) and the Brazilian Securities and Exchange Commission (“SEC”). In order to comply with good market practices, the company adopts as a principle the simultaneous disclosure of its financial information in both markets, in reais, in Portuguese and English.

On March 31, 2026, TIM holds a 49% equity interest (49% on December 31, 2025) in the company I-Systems (associated company) and 100% at the company V8.Tech Consulting S.A. (“V8”), fully-controlled subsidiary.

1.2. Business combination (IFRS 3/CPC 15 (R1))

1.2.1. Transaction description

On November 26, 2025, the Company’s Board of Directors approved the acquisition of 100% of the share capital of V8 Consulting S.A. (“V8.Tech” or “acquiree”), a technology company founded in 2014, specialized in the integration of digital solutions and managed services, with additional variable payments (earn-outs) expected. The operation, aligned with TIM’s strategy to strengthen the B2B segment, was subject to the fulfillment of precedent conditions, including approval by CADE on December 19, 2025, and the fulfillment of other conditions. The closing of the acquisition by TIM took place on January 30, 2026, from which date the Company gained control of the acquired entity.

1.2.2. Consideration transferred

The consideration transferred for the acquisition was composed as follows:

(i) After the completion of the usual price adjustments of the transaction, an initial payment of R$ 100 million was set on the closing date, of which R$ 9.9 million remained withheld for coverage of potential future price adjustments, classified as “Other liabilities and provision”. Thus, the amount actually paid in cash on the acquisition date totaled approximately R$ 90 million, with the retained amount of 9.9 million being settled later, in April 2026.

(ii) The acquisition agreement provides for variable additional payments (earn-outs), conditioned on the achievement of predefined targets until 2030. At the acquisition date, the contingent consideration was measured at fair value, according to CPC 15 / IFRS 3, in the amount of R$ 66 million. Said amount was included in the total recognized consideration measured. The contingent consideration was classified as financial instruments and recorded as “Other liabilities and provision.”

As of January 31, 2026, the total consideration transferred for the acquisition of V8 was R$ 166 million.

1.2.3. Assets acquired and liabilities assumed

Management used the balance sheet as of January 31, 2026, as the basis for the transaction, the fair value of the identifiable assets acquired and liabilities assumed from V8. Tech on the date of the acquisition by TIM S.A. is being prepared and finalized according to the Price purchase allocation report and may be changed until the final conclusion, which may occur up to 12 months from the acquisition date. On this date, the preliminary analysis indicates assets and liabilities presented below:

(i) It mainly includes intangible assets identified in the business combination – Customer relationship.

As part of the preliminary allocation of the purchase price, the intangible asset Customer relationship was identified and recognized separately from Goodwill, in the amount of R$ 38,031. Its evaluation was based on assumptions and projections adopted by the Company’s Management in the V8 Business Enterprise Valuation (BEV), with an estimated remaining useful life of 11.92 years, which was used to determine the purchase price of the transaction.

(ii) It mainly represents the deferred income tax and social contribution liability established due to the recognition of the intangible assets of Customer relationship at fair value on the acquisition date, calculated based on the current rates, totaling R$ 12,931.

The assets acquired and liabilities assumed related to the acquisition of V8.Tech (net assets) by TIM on the acquisition date, as well as the impacts on the Company’s consolidated income or loss, are summarized below.

1.2.4. Goodwill

The goodwill resulting from the acquisition was determined as follows:

The recognized goodwill mainly arises from the expected operational synergies with the Group’s existing businesses, the expansion of the customer base and the B2B solutions portfolio, as well as the specialized workforce and technical knowledge of the acquired company. Goodwill is allocated on a consolidated basis as the assets acquired and liabilities assumed bring benefits to the business as a whole.

The individual and consolidated quarterly information was prepared and is being presented according to the accounting practices adopted in Brazil, which comprise the CVM standards and pronouncements, guidance and interpretations issued by the Accounting Pronouncement Committee (“CPC”) and in compliance with the International Financial Reporting Standards (IFRS) issued by the International Accounting Standards Board (IASB).

Additionally, the Company considered the guidelines provided for in Technical Guideline OCPC 07 - Evidencing upon Disclosure of General Purpose Financial-Accounting Reports in the preparation of its financial statements. Accordingly, relevant information of the quarterly information is being evidenced and corresponds to the information used by management when administrating.

The material accounting policies applied in the preparation of this quarterly information are below and/or presented in its respective notes. Those policies were consistently applied in the periods presented.

a. General criteria for preparation and disclosure

The individual and consolidated quarterly information was prepared considering the historical cost as value basis, except regarding the derivative financial instruments that were measured at fair value.

Assets and liabilities are classified according to their degree of liquidity and collectability. They are reported as current when they are likely to be realized or settled over the next 12 months. Otherwise, they are stated as non-current. The exception to this procedure involves deferred income tax and social contribution balances (assets and liabilities) and provision for lawsuits and administrative proceedings that are fully classified as non-current.

In connection with the preparation of this quarterly information, Management concluded that there is no evidence of uncertainties about the Company’s going concern. Therefore, the quarterly information was prepared based on the going concern assumption.

The presentation of the Statement of Value Added is required by Brazilian corporate law and the accounting practices adopted in Brazil applicable to publicly-held companies. The DVA was prepared according to the criteria set forth in CPC Technical Pronouncement No. 09 - “Statement of Value Added”. The IFRS do not require the presentation of this statement. Consequently, according to IFRS, this statement is presented as supplementary information, without prejudice to the set of quarterly information.

Interests paid from loans and financing are classified as financing cash flow in the statement of cash flow as it represents costs of obtaining financial resources.

b. Functional and presentation currency

The currency of presentation of the quarterly information is the Real (R$), which is also the functional currency of the Company, subsidiary and associated company.

Transactions in foreign currency are recognized by the exchange rate on the date of transaction. Monetary items in foreign currency are translated into Brazilian reais at the foreign exchange rate prevailing on the balance sheet date, informed by the Central Bank of Brazil. Foreign exchange gains and losses linked to these items are recorded in the statement of income.

Operating segments are components of the entity that carry out business activities from which revenues can be obtained and expenses incurred. Its operating results are regularly reviewed by the entity's main operations manager, who makes decisions on resource allocation and evaluates segment performance. For the segment to exist, individualized financial information is required.

The main operational decision maker in the Company, responsible for the allocation of resources and periodically evaluating performance, is the Executive Board, which, along with the Board of Directors, are responsible for making the strategic decisions of the company and its management.

The Company’s strategy is focused on optimizing results. Although there are diverse operating activities, decision makers understand that the company represents only one business segment and do not contemplate specific strategies focused only on one service line. All decisions regarding strategic, financial planning, purchases, investments and investment of resources are made on a consolidated basis. The aim is to maximize the result obtained by operating the SMP, STFC and SCM licenses.

Subsidiaries are all entities over which the Group has control. The Group controls an entity when it is exposed to, or has a right over the variable returns arising from its involvement with the entity and has the ability to interfere in those returns due to its power over the entity. The subsidiaries are fully consolidated as of the date control is transferred to the Group. Consolidation is interrupted beginning as of the date in which the Group no longer holds control.

If the Group loses control exercised over a subsidiary, the corresponding assets (including any goodwill) and liabilities of the subsidiary are written-off at their book values on the date the control is lost, and the write-off of the book value of any non-controlling interests on the date when control is lost (including any components of other comprehensive income attributed to them) also occurs. Any difference resulting as gain or loss is accounted for in the income statement. Any investment held is recognized at its fair value on the date control is lost.

Intercompany transactions, as well as the balances and unrealized gains and losses in those transactions, are eliminated. The base date of the financial information used for consolidation purposes is the same for all the companies in the Group.

The Company’s consolidation basis on March 31, 2026 includes the wholly-owned subsidiary V8 (100% equity interest), acquired on January 30, 2026.

Business combinations are accounted for under the acquisition method. The cost of an acquisition is measured for the consideration amount transferred, which is valuated on fair value basis on the acquisition date, including the value of any non-controlling interest in the acquiree, regardless of their proportion. For each business combination the Company chooses to measure the non-controlling interest in the acquiree at the fair value or based on its proportional interest in the net assets identifiable of the acquiree. Costs directly attributable to the acquisition are accounted for as expense when incurred.

On acquiring a business, the Company assesses the financial assets and liabilities assumed in order to rate and to allocate them in accordance with contractual terms, economic circumstances and pertinent conditions on the

acquisition date, which includes segregation by the acquired entity of built-in derivatives existing in the acquired entity’s host contracts.

Any contingent payments to be transferred by the acquiree will be recognized at fair value on the acquisition date. Subsequent changes to the fair value of the contingent consideration which is deemed to be a liability should be recognized in accordance with CPC 48 in the statement of income.

Initially, goodwill is initially measured as being the excess of consideration transferred in relation to net assets acquired (acquired identifiable assets and assumed liabilities) measured at fair value on acquisition date. If consideration is lower than fair value of net assets acquired, the difference must be recognized as gain in bargain purchase in the statement of income on the acquisition date.

After initial recognition, the goodwill is carried at cost less any accumulated impairment losses. For impairment testing purposes, goodwill acquired in a business combination is, from the acquisition date, allocated to each cash-generating units of the Company that are expected to benefit by the synergies of combination, regardless of other assets or liabilities of the acquiree being allocated to those units.

When the goodwill is part of a cash generating unit and a portion of this unit is disposed of, the goodwill associated with the disposed portion should be included in the cost of the operation when calculating gains or losses in the disposal. The goodwill disposed under these circumstances of this operation is determined based on the proportional values of the portion disposed of, in relation to the cash generating unit maintained.

This individual and consolidated quarterly information was approved by the Company's Board of Directors on May 5, 2026.

g.1 The following new standards/amendments were issued by the Accounting Pronouncement Committee (“CPC”) and International Accounting Standards Board (IASB), are effective for the period ended March 31, 2026.

Amendments to IFRS 9 and IFRS 7 - Amendments to the Classification and Measurement of Financial Instruments

In May 2024, the International Accounting Standards Board (IASB) issued amendments to IFRS 9 and IFRS 7 – Amendments to the Classification and Measurement of Financial Instruments, which introduce relevant modifications to the classification, measurement, and disclosure requirements of financial instruments. In line with these changes, the Accounting Pronouncement Committee - CPC should incorporate the changes through future revisions of the CPC 48 – Financial Instruments and CPC 40 (R1) – Financial Instruments: Evidencing

The main changes introduced are as follows:

• A clarification that a financial liability is written off on the “settlement date” and the introduction of an accounting policy option (when certain conditions are met) to write off financial liabilities settled through an electronic payment system before the settlement date.

• Additional guidance on how contractual cash flows from financial assets with environmental, social and corporate governance (ESG) and similar characteristics should be evaluated.

• Clarifications on what constitutes “non-recourse characteristics” and what are the characteristics of contractually binding instruments.

• Introduction of new disclosure requirements for financial instruments with contingent characteristics and additional disclosure requirements for equity instruments measured at fair value through other comprehensive income (OCI).

The amendments are applicable for annual periods beginning on or after January 1, 2026, with early adoption allowed only for the classification of financial assets and the related disclosures.

The Company assessed and did not identify any impact on its quarterly information.

Annual Improvements to IFRS Standards – Volume 11

In July 2024, the IASB issued nine narrow-scope amendments as part of its periodic maintenance of the IFRS standards. The amendments include clarifications, simplifications, corrections, or modifications intended to improve the consistency of the following standards: IFRS 1 – First-time Adoption of International Financial Reporting Standards (equivalent to CPC 37 (R1) – First-time Adoption of International Accounting Standards), IFRS 7 – Financial Instruments: Disclosure (equivalent to CPC 40 (R1) – Financial Instruments: Disclosure) and its Guidance for the Implementation of IFRS 7, IFRS 9 – Financial Instruments (equivalent to CPC 48 – Financial Instruments), IFRS 10 – Consolidated Financial Statements (equivalent to CPC 36 (R3) – Consolidated Statements) and IAS 7 – Statement of Cash Flow (equivalent to CPC 03 (R2) – Statement of Cash Flow).

In line with these updates, the Accounting Pronouncement Committee - CPC should reflect such changes in future revisions of the corresponding technical pronouncements. The amendments will be effective for reporting periods starting on or after January 1, 2026. Early adoption is permitted, which must be disclosed.

The Company assessed and did not identify any impact on its quarterly information.

g.2 the following new standards were issued by Comitê de Pronunciamentos Contábeis [Accounting pronouncements committee] (CPC) and the International Accounting Standards Board (IASB), but are not in effect for the period ended on March 31, 2026. The Company intends to adopt these new and amended standards and interpretations, if applicable, when they come into force.

IFRS 18 (equivalent to CPC 51): Presentation and disclosure of financial statements

In April 2024, the IASB issued IFRS 18, which replaces IAS 1 (equivalent to CPC 26 (R1) - Presentation of Financial Statements). IFRS 18 introduces new requirements for presentation within the statement of income, including specified totals and subtotals. Moreover, entities are required to classify all revenues and expenses within the statement of income in one of five categories: operating, investment, financing, income taxes and discontinued operations, of which the first three are new.

The standard also requires the disclosure of performance measures defined by management, subtotals of revenues and expenses, and includes new requirements for the aggregation and disaggregation of financial information based on the identified “functions” of the primary financial statements (PFS) and notes.

Furthermore, restricted scope amendments were made to IAS 7 (equivalent to CPC 03 (R2) - Statement of Cash Flows), which include changing the starting point for determining cash flows from operations using the indirect method, from “income or loss for the period” to “operating income +r loss” and removing the option to classify cash flows from dividends and interest. In addition, there are consequent amendments in several other standards.

The adoption of IFRS 18 does not change the values of assets, liabilities, or shareholders’ equity, but it significantly impacts the way the financial statements are presented. The main change occurs in the Statement of Income, which now presents revenues and expenses classified into operational, investment, and financing categories, in addition to the inclusion of the mandatory subtotals of Operating Profit and Profit before Financing and Income Tax. This restructuring implies the reallocation of items previously presented as financial income (loss), according to the new definitions.

In summary, the expected effects on the Company focus on the presentation and transparency of information, with no impact on net profit or shareholders’ equity, but with a need to adjust the notes and internal systems for the classification of transactions according to the new categories.

The Company is currently working to identify all the impacts that the changes will have on the primary financial statements and notes to the financial statements. The initial expected material impacts on the Company’s financial statements are as follows:

• The foreign exchange variation differences will be classified in the category of the statement of income (revenue and expenses) in which the items that gave rise to such exchange differences are located.

• New announcements will be included, comprising: (a) Management-defined performance measures (MPMs); (b) specific expenses by nature, if expenses are presented by function in the operating category of the statement of income; and (c) a reconciliation, for each line of the statement of income, between the restated amounts in accordance with IFRS 18 and the amounts previously presented in accordance with IAS 1 (CPC 26 (R1).

• Interest received and interest paid will be classified, respectively, in investing activities and financing activities in the statement of cash flow, according to CPC 03 (R2) – Statement of Cash Flows.

• Goodwill will be presented separately in the financial statements, in accordance with the new presentation requirements introduced by IFRS 18.

IFRS 18 and the amendments to the other standards will come into force for reporting periods beginning on or after January 1, 2027, with early adoption permitted, and must be disclosed, although in Brazil early adoption is not allowed. IFRS 18 will be applied retrospectively.

Amendment IAS 21 – Conversion of financial statements to a non-hyperinflationary currency

In November 2025, the IASB issued amendments to IAS 21, providing additional guidance on how entities should convert financial statements prepared in a non-hyperinflationary currency to a hyperinflationary presentation currency.

These specific changes aim to improve the quality of information and reduce the diversity of practices, providing greater consistency in the preparation of reports in hyperinflationary economies.

The amendments to IAS 21 – Effects of Changes in Foreign Exchange Rates – are effective for annual periods beginning on or after January 1, 2027, with early adoption permitted.

The Company assessed and did not identify any impact on its quarterly information.

Accounting estimates and judgments are continuously assessed based on the Company's historical experience and on other factors, such as expectations of future events, considering the circumstances present on the base date of quarterly information.

By definition, resulting accounting estimates are seldom equal to the respective actual income (loss). The estimates and assumptions that present a significant risk, with the probability of causing a material adjustment to the book values of assets and liabilities for the fiscal period, are covered below.

(a)       Provision for legal and tax administrative proceedings

The legal and tax administrative proceedings are analyzed by the Management along with its legal advisors (internal and external). The Company considers factors in its analysis such as hierarchy of laws, precedents available, recent court judgments, their relevance in the legal system and payment history. These assessments involve Management’s judgment (note 23).

(b)       Fair value of derivatives and other financial instruments

The financial instruments presented in the balance sheet at fair value are measured using valuation techniques that consider observable data or observable data derived from market (Note 36).

(c)       Unbilled revenues

Since some cut dates for billing occur at intermediate dates within the months of the year, as the end of each month there are revenues earned by the Company, but not actually invoiced to its customers. These unbilled revenues are recorded based on estimate that takes into consideration historical consumption data, number of days elapsed since the last billing date, among others (note 27).

(d)       Leases

The Company has a significant number of the lease contracts in which it acts a lessee (Note 17), and with the adoption of the accounting standard IFRS 16 / CPC 06 (R2) – Leases, on January 1, 2019, certain judgments were exercised by Company’s management in measuring lease liabilities and right-of-use assets, such as: (i) estimate of the lease term, considering non-cancellable period and the period covered by options to extend the contract term, when the exercise depends only from the Company, and this exercise is reasonably certain; and (ii) using certain assumptions to calculate the discount rate.

The company is not able to readily determine the interest rate implicit on the lease and, therefore, considers its incremental rate on loans to measure lease liabilities. Incremental rate on the lessee’s loan is the interest rate that the lessee would have to pay when borrowing, for a similar term and with a similar guarantee, the resources

necessary to obtain the asset with a value similar to the right of use asset in a similar economic environment. The Company estimates the incremental rate using observable data (such as market interest rates) when available and considers aspects that are specific to the Company (such as the cost of debt) in this estimate.

(e)       Business combination

Business combinations are accounted for under the acquisition method. The cost of an acquisition is measured for the consideration amount transferred, which is valuated on fair value basis on the acquisition date, including the value of any non-controlling interest in the acquiree, regardless of their proportion. For each business combination the Acquirer must measure the non-controlling interest in the acquiree at the fair value or based on its interest in the net assets identified in the acquiree. Costs directly attributable to the acquisition are accounted for as expense when incurred. For further information, see Notes 1.2. and 2.e.

Cash and cash equivalents are financial assets measured at amortized cost or at fair value through profit or loss, respectively.

Company’s Management classifies its financial assets upon initial recognition.

Bank certificates of deposit (“CDBs”) are nominative securities issued by banks and sold to the public as a form of fund raising. These securities can be traded during the contracted term, at any time, which gives them high liquidity, their adjustment is linked to the percentage of the Interbank Deposit Certificate (CDI), there is no risk of significant impairment in their value and they are used to fulfill the Company’s short-term obligations.

The average remuneration of CDB investments in the year ended March 31, 2026 is 100.71% p.a. (100.49% on December 31, 2025) of the variation of the Interbank Deposit Certificate - CDI.

Comprise financial assets measured at fair value through profit or loss.

Parent Company Consolidated

(i) Since 2017, the Company, with the aim of supporting the National Film Industry Financing Fund, as well as using tax deductibility benefit for income tax purposes, started investing in the National Film Industry Financing Fund (FUNCINE). The average remuneration for the period ended March 31, 2026, was 0.08% p.a. (0.17% p.a. on December 31, 2025).

(ii) Fundo Soberano is composed only of federal government bonds. The average remuneration of FICs in the period ended March 31, 2026 was 99.83% p.a. of the variation of the Interbank Deposit Certificate - CDI (99.30% p.a. on December 31, 2025).

(iii) It is represented by non-exclusive Investment funds in units.

(iv) The Company invests in exclusive FICs (Quota Investment Fund). Funds are mostly made up of federal government bonds and papers from financial institutions, mostly AAA (highest quality). The average remuneration of FICs in the period ended March 31, 2026 was 101.06% p.a. of the variation of the Interbank Deposit Certificate - CDI (101.99% p.a. on December 31, 2025).

(a) Government bonds are fixed income financial instruments issued by the National Treasury to finance the activities of the Federal Government.

(b) CDBs are securities issued by banks with the commitment of buyback by the bank itself, having their correction linked to the percentage of the Interbank Deposit Certificate (CDI).

(c) The Financial bills is a fix income tittle emitted by financial institutions.

(d) Is represented by: Debentures, FIDC, commercial notes, promissory notes, bank credit note.

These are financial assets measured at amortized cost, and refer to accounts receivable from users of telecommunications services, from network use (interconnection) and from sales of handsets and accessories. Accounts receivable are recorded at the price charged at the time of the transaction. The balances of accounts receivable also include services provided and not billed (“unbilled”) up to the balance sheet date. Trade accounts receivable are initially recognized at fair value and, subsequently, measured at amortized cost using the effective interest rate method less provision for expected credit losses (“impairment”).

The provision for expected credit losses was recognized as a decrease in accounts receivable based on the profile of the subscriber portfolio, the aging of overdue accounts receivable, the economic situation, the risks involved in each case and the collection curve, at an amount deemed sufficient by Management, as adjusted to reflect current and prospective information on macroeconomic factors that affect the customers’ ability to settle the receivables.

The fair value of trade accounts receivable is close to the book value recorded on March 31, 2026 and December 31, 2025.

Amounts expected to be received in more than 12 months are classified as long-term.

The average rate considered in calculating the present value of accounts receivable recorded in the long term is 0.58% p.m. (0.58% p.m. on December 31, 2025).

The movement of the provision for expected credit losses, accounted for as an asset reduction account, was as follows:

The aging of accounts receivable is as follows:

Parent company Consolidated

Inventories are presented at the average acquisition cost. A loss is recognized to adjust the cost of Handsets and accessories to the net realizable value (selling price) when this value is less than the average acquisition cost.

In 2025, the Company recognized IRPJ credits amounting to R$ 81 million, resulting from the success in a lawsuit that discussed the limitation on the calculation of tax incentives, with the amount of R$ 34 million offset by March 31, 2026. Additionally, as a result of this decision, the tax loss base was recomposed of R$ 224 million, which was fully offset in 2025.

The Company has balances to offset of IRPJ and CSLL amounting to R$ 223 million on March 31, 2026 (R$ 220 million on December 31, 2025) resulting from overpayment in prior periods for which refund processes are underway.

In the first quarter of 2026, the Company made an advance through deposits in Banco do Nordeste, totaling R$ 11 million (R$ 31 million as of December 31, 2025), with the objective of using the reinvestment tax incentive, which allocates a portion of the IRPJ due to a specific deposit, in accordance with article 668 of RIR/2018.

Current income tax and social contribution charges are calculated on the basis of the tax laws enacted, or substantially enacted, up to the balance sheet date.

The legislation allows companies to opt for quarterly or monthly payment of income tax and social contribution. In 2026, the Company has chosen to make the quarterly payment of income tax and social contribution.

8.c Deferred income tax and social contribution

Deferred income tax and social contribution are recognized on (1) tax losses and accumulated tax loss carryforwards, when applicable; and (2) temporary differences arising from differences between the tax basis of assets and liabilities and their book values in the quarterly information. Deferred income tax is determined using the tax rates (and tax laws) enacted, or substantially enacted, up to the balance sheet date. Subsequent changes in tax rates or tax legislation may modify the deferred tax credit and debit balances.

Deferred tax assets on income tax and social contribution are recognized only according to the profitable track record and/or when based on the annual forecasts prepared by the Company.

The balances of deferred income tax assets and liabilities are presented at net value in balance sheet when there is the legal right and the intention of offsetting them upon calculation of current taxes, in general related to the same legal entity and the same tax authority. Accordingly, deferred tax assets and liabilities in different entities are in general presented separately, and not at net balance.

On March 31, 2026 and December 31, 2025, the prevailing tax rates were 25% for income tax and 9% for social contribution. In addition, there is no statute of limitation in regard to the income tax and social contribution carried forward losses, which it can be offset by up to 30% of the taxable profit reached at each fiscal year, according to the current tax legislation.

The amounts recorded are as follows:

Parent Company Consolidated

(i) Mainly represented by the Fistel fee (TFF) for the financial years 2020-2026 of TIM S.A. and the TFF referring to Cozani's 2022 financial year. The Operating Inspection Fee (TFF) for the years 2020 and 2026 of TIM S.A. and TFF for 2022 of Cozani had its payments suspended by virtue of an injunction and, therefore, still do not have a specific date for payment. See note 21 for details.

(ii) Represents the effect of deferred income tax and social contribution on lease contracts. The temporary difference of the IFRS 16 contracts is due to the difference in the timing of recognition of the accounting (interest and depreciation) and tax expense (provision of service), under the terms of the current legislation. Amortization occurs on a straight-line basis according to the execution of the contract over time.

(iii) As of the 1Q20, TIM S.A. excludes the portion of acceleration of depreciation of movable assets belonging to property, plant and equipment from the calculation basis of the IRPJ and CSLL, due to their uninterrupted use in three operating shifts, supported by technical expert report, as provided for in Article 323 of the RIR/2018, or by the adequacy to the tax depreciation provided for in IN 1700/2017.

(iv) Refers to deferred charges on the adjustment at fair value of the non-controlling interest calculated in the sale of Fiber Co (currently I-Systems), which took place in November 2021, from TIM S.A. to IHS Fiber Brasil - Cessão de Infraestruturas Ltda (see Note 14).

(v) Represents the deferred charges recorded, referring to the impairment of tangible assets recognized by Cozani before its acquisition in April 2022, which has been depreciated over the estimated useful life of the asset.

The Company based on a history of profitability and based on projections of future taxable results, constitutes deferred income tax credits and social contribution on all of its temporary differences.

8.d Expenses with current and deferred income tax and social contribution

The reconciliation between income tax and social contribution expense as calculated by applying combined tax rates and amounts reflected in income (loss) is as follows:

The Company considered the amendments to IAS 12 (equivalent to CPC 32 – Income taxes) introduced in response to the OECD Pillar Two rules. During the year 2025, the Company has not identified any significant impacts resulting from these changes. During the year 2026, the company is beginning analyses to assess possible impacts.

(a) credits on the acquisition of property, plant and equipment directly related to the provision of telecommunication services (credits divided over 48 months).

(b) ICMS amounts paid under the tax substitution regime from goods acquired for resale, mainly mobile handsets, chips, tablets and modems sold by TIM.

(i) The Fistel rate is appropriated monthly to the income (loss).

(ii) Represent prepaid payments of advertising expenses for products and services of the TIM brand that are recognized in the result according to the period of serving the advertisement.

(iii) It is substantially represented by incremental costs related to sales commissions paid to partners for obtaining customer contracts arising from the adoption of IFRS 15/ CPC 47, which are deferred to the result in accordance with the term of the contract and/or economic benefit, usually from 1 to 2 years.

(iv) Represent the costs of installing a neutral network deferred over the term of the contract.

They are recorded at historical cost and updated according to current legislation.

(i) Refer to legal blockages directly in the company's current accounts and interest earning bank deposits linked to certain legal proceedings. This amount is periodically analyzed and when identified, reclassification is made to one of the other specific accounts of the legal deposit item.

Civil

These are court deposits to guarantee the execution of civil proceedings where the Company is challenging the amounts involved. Most of these proceedings refer to lawsuits filed by customers, involving issues of consumer rights, among others.

Labor

These are amounts deposited in court as guarantees for the execution and the filing of appropriate appeals, where the relevant matters or amounts involved are still being discussed. The total amount has been allocated between the various claims filed by registered employees and third-party service providers.

Tax

The Company has legal deposits in the total, restated and estimated amount of R$ 260,043 (R$ 254,927 on December 31, 2025), relating to tax matters, made to support several ongoing legal discussions. Such deposits mainly relate to the following discussions:

They are recognized at fair value on the date of acquisition or issue. Such financial assets are subsequently measured at fair value through profit or loss. Changes arising from the fair value measurement, where applicable, shall be recognized in the result when incurred, under the line of financial income (loss). The Company must disclose the level classification of each financial instrument. See Note 36 in the section on Financial instruments measured at fair value for details of this information.

(ii) Up to December 31, 2025, the Company made contributions in dollars, equivalent to approximately R$ 270 million in the Investment fund focused on 5G solutions “Upload Ventures Growth” (“5G Fund”), reinforcing its commitment to boosting the development of solutions based on 5G technology; thus, concluding the contributions provided for. There were no new contributions in 2026.

(ii) In April 2022, the Company entered into a partnership with EXA Serviços de Tecnologia (“EXA”) to provide digital services and entertainment to TIM’s customer base. Said partnership also provided for commission payments by EXA to TIM as a result of TIM’s customers that acquire services from this partnership, as well as TIM’s right to subscribe to shares upon payment of a consideration.

At the end of 2024, the contract with the new partnership terms was completed and TIM acquired the right to subscribe for 27% of EXA’s shares for a consideration of R$ 174 million. The value of the financial asset was recorded at fair value for R$ 175 million and accounts for 27% of the fair value of TIM’s right to participate in EXA. Starting from March 31, 2026, this right may be exercised within the next 9 months upon the fulfillment of exercise conditions and corporate approval.

The financial assets related to Fundo 5G and Subscription warrant were assessed in accordance with the applicable accounting practices, including with respect to fair value measurement, as provided for in the current accounting pronouncements.

The ownership interest in associated company and subsidiary is valued using the equity accounting method.

V8.Tech

As mentioned in Note 1.2, on January 30, 2026, after the applicable precedent conditions were met, TIM S.A. completed the acquisition of 100% of the share capital of V8.Tech. With the completion of the operation, TIM S.A. now holds all the share capital of V8.Tech, a technology company specialized in the integration of digital solutions and the rendering of managed services. Thus, as of March 31, 2026, V8.Tech is classified as a subsidiary of TIM S.A.

I-Systems

In November 2021, as a result of the spin-off of net assets from the broadband business and creation of I-Systems, TIM S.A. disposed of 51% of its equity interest on behalf of IHS. As a result of this transaction, a loss of control took place and TIM S.A. no longer consolidates the Company, recording at the time, the investment in the associated company in the amount of R$ 1,612,957, at fair value, for the remaining minority interest (non-controlling) of 49%.

TIM S.A. has 49% (49% on December 31, 2025) in the share capital of I-Systems. The following table represents summarized financial information about the investments of I-Systems: