The Year of the Judiciary is just beginning, but in its first face -to -face sessions, the Federal Supreme Court (STF) resumed the trial of two extremely relevant topics in the tax area, with a tragic outcome for taxpayers on Wednesday -Lindo (8). After this result, not even res judicata decisions will be definitive. It is a dangerous path towards legal insecurity.

Themes Numbers 881 and 885 refer to the boundaries of the thing judged in tax matters and seek to define what happens when, in a change of understanding, a subject that until then benefited taxpayers (therefore, recognizing the unconstitutionality of collection of tax) becomes favorably judged to the tax authorities (ie, with the recognition of its constitutionality).

In practice, this is the following situation: a taxpayer filed a lawsuit and had a favorable trial, including res judicata. However, after this final decision, the Supreme Court concluded that the collection of the tax was constitutional. What will happen to who filed the action and was not paying the tribute?

According to the Supreme Court's understanding, the subsequent judgment will annul all previous, albeit definitive decisions for the plaintiff. That is, the individual or legal entity will need to collect the tax again. And, considering that there was no modulation of the effects, the return to the payment should occur immediately after the publication of the decision that considers the payment of the tax, safeguarding the application of the principles of annual and nonagesimal priority.

In this case, equality is preserved among taxpayers, leaving all subject to the same tax burden. However, the legal certainty is impaired, since the taxpayer who filed the lawsuit may not provide until when he may earn the economic benefit guaranteed to him in court. In Brazil, therefore, even the past is uncertain.