The Federal Supreme Court (STF) has not yet issued a ruling
On 10/08/2014, the Full Bench of the Federal Supreme Court continued the trial of Extraordinary Appeal No. 240.785, after almost 16 years, in which the constitutionality of including the ICMS in the tax base for COFINS was discussed.
At that trial, the prevailing understanding was that the ICMS cannot be included in the tax base for COFINS because the ICMS is not a taxpayer revenue.
It should be noted, however, that the majority was obtained through votes previously cast by Justices who have since retired from the Supreme Court. And the ruling in that appeal only applied to a single case, as it was not part of a general recovery action and neither a case of constitutional review (such as ADI ou ADC).
If only the current composition of the Supreme Court is to be considered, the score is 4 to 1, with Justices Marco Aurélio, Cármen Lúcia, Ricardo Lewandowski and Celso Mello voting in favor of the taxpayers, and Gilmar Mendes in favor of the Public Treasury.
A definition of the Supreme Court thesis will need to await the vote of Justices Luis Roberto Barroso, Rosa Weber, Teori Zavaski, Luiz Fux, Dias Toffoli (who may recuse himself in ADC No. 18 – Declaratory Act of Constitutionality No. 18), and, perhaps, Justice Joaquim Barbosa’s replacement, who has not yet been chosen by the President.