STF denies ADC No. 98 and keeps open the discussions on the PIS and COFINS calculation basis

On May 6, 2026, Justice Nunes Marques, rapporteur of ADC No. 98 at the Federal Supreme Court, denied the action filed by the Presidency through the Office of the Attorney General (AGU), which sought a declaration of constitutionality of article 1 of Law 10.637/2002, article 1 of Law 10.833/2003 and article 2 of Law 9.718/1998, with the goal of broadly validating the inclusion of tax amounts in the PIS and COFINS calculation basis. The initiative emerged in the context of the so-called "spinoff theses" of Topic No. 69 of general repercussion, in which the STF decided to exclude ICMS from the basis of those contributions.

In the proceeding, the AGU argued that the line of reasoning behind the Topic No. 69 precedent was being used to expand discussions on the exclusion of other amounts from the PIS and COFINS basis, generating legal uncertainty and a high volume of litigation. With that, the action sought to have the STF immediately recognize the constitutionality of including ISS (Topic No. 118), presumed ICMS credits (Topic No. 843) and PIS and COFINS themselves (Topic No. 1.067) in the basis of these contributions.

In rejecting the ADC, Justice Nunes Marques found that the Union had not demonstrated a specific judicial controversy on the constitutionality of the cited provisions, but only a generic scenario of growing tax disputes after Topic No. 69 — which would not justify discussion through a Declaratory Action of Constitutionality, since it does not shake the presumption of constitutionality of the PIS and COFINS rules. According to the rapporteur, the action merely sought to anticipate the judgment of topics already under the general-repercussion procedure, creating undue overlap between concentrated review and the extraordinary appeals already pending at the STF.

From a practical standpoint, the decision keeps active the discussions on the inclusion of ISS, PIS/COFINS and presumed ICMS credits in the calculation basis of the contributions, so that the AGU's strategy of obtaining a broad, early definition favorable to the Federal Treasury — before the specific judgment of those topics — ended up rejected by the STF, which signaled the need for individualized analysis of each controversy.

Although there was no analysis of the merits of the tax theses pointed out by the AGU as threats, the decision represents a relevant opportunity for taxpayers and the business sector: through it, the STF indicated that it will not allow procedural shortcuts to close discussions still pending judgment, and preserved the right of each thesis to be examined in its proper procedure — allowing taxpayers to continue defending their arguments in ongoing cases and preserving its sovereignty as a supreme court.