The transition to the new consumption tax system raises a relevant issue for taxpayers: should IBS and CBS, the new taxes introduced by the Tax Reform, be included in the ICMS tax base during the period in which the old and new taxes will coexist?
The issue becomes particularly relevant as of 2027, when IBS and CBS will become effectively payable, while ICMS will remain in force during the transition period.
The São Paulo State Treasury (Sefaz-SP) has already expressed a position in favor of including these amounts in the ICMS tax base. In responses to tax consultations, Sefaz-SP maintains that, once they become effectively payable, IBS and CBS will form part of the value of the transaction or service and, consequently, of the tax base of the state tax.
Against this backdrop, a recent decision by the São Paulo courts is particularly relevant. In a preliminary injunction granted in a writ of mandamus, the 16th Public Treasury Court of São Paulo excluded, for the company that filed the action, the inclusion of IBS and CBS in the ICMS tax base as of 2027. The decision marks the beginning of an important judicial discussion on the matter, although its effects are limited to the specific case.
Under the Consumption Tax Reform, established by Constitutional Amendment No. 132/2023 and regulated, among other provisions, by Complementary Law No. 214/2025, Brazil is adopting a dual VAT system, consisting of two new taxes: CBS (Contribution on Goods and Services), a federal tax that will replace PIS and Cofins; and IBS (Tax on Goods and Services), a tax imposed by the states, the Federal District, and municipalities that will gradually replace ICMS and ISS.
The replacement will take place gradually, with a transition period from 2026 to 2033 during which the old and new tax systems will coexist.
It is precisely this coexistence between the different systems that gives rise to the controversy addressed in this legal update.
The discussion concerns the composition of the ICMS tax base itself. On the one hand, the São Paulo State Treasury takes the position that, once IBS and CBS become effectively due, these amounts should be included in the value of the transaction or service and, therefore, in the ICMS tax base. On the other hand, taxpayers argue that including the new taxes in the tax base of the state tax requires an express statutory provision, particularly in light of the principle of tax legality.
On September 9, 2026, the judge of the 16th Public Treasury Court of São Paulo granted a preliminary injunction in a preventive writ of mandamus filed by Privalia Brasil S.A. (Case No. 1138866-98.2026.8.26.0053), securing the company’s right to calculate and pay ICMS without including IBS and CBS in its tax base once these new taxes become effectively due, as of 2027, and for as long as they coexist with ICMS. The decision also prohibits the State Treasury from imposing any penalties, including tax assessments, fines, denial of tax clearance certificates, or enrollment in tax debt, based solely on the failure to include the new taxes in the ICMS tax base.
The central ground of the court’s decision is the principle of legality. Any increase in a tax or change that results in a higher tax burden must be expressly provided for by law (Article 150, I, of the Federal Constitution; Article 97, IV and §1, of the National Tax Code). The determination of the tax base of taxes is also reserved to complementary law (Article 146, III, “a”, of the Federal Constitution). In the absence of a statutory provision, the tax cannot be imposed.
The São Paulo decision is the first favorable ruling for taxpayers reported to date and indicates that the matter remains subject to judicial review and will likely ultimately be addressed by higher courts.
The preliminary injunction protects only the company that filed the lawsuit, given that its effects are limited to the individual dispute. Other taxpayers would need to bring their own legal proceedings to seek the same protection.
The practical effects of including IBS and CBS in the ICMS tax base will begin to be felt in 2027. In 2026, IBS and CBS are subject to informational rates of 0.1%, with effective payment waived provided that the applicable ancillary tax obligations are duly complied with.
Potential financial impact: if IBS and CBS are included in the ICMS tax base, the state tax will be calculated on a higher amount, increasing the tax burden on each transaction. The impact will vary depending on the product, state, and tax regime applicable.
Accordingly, taxpayers should assess the possibility of pursuing preventive legal measures to secure their right not to be required to include IBS and CBS in the ICMS tax base.
BVP Advogados Associados remains available to assist you with this developing matter.
Rua Oscar Freire 2250, 2º andar
Pinheiros, São Paulo – SP
CEP 05409-011