Targowica Confederation
He also joined the Targowica-Grodno Deputation ("Deputacja Targowicko-Grodzieńska"), which was set up to control the Targowica Confederation and the Grodno Sejm activity. Tański signed the report of this Deputation, that was submitted on July 26, 1794 to the Military Criminal Court. He also helped to prepare an alphabetical list of names of people who were in any way engaged in the Targowica Confederation, and thus were recognized as ones that should not hold public trust offices. Tables of 9 September 1794 with Tański's signature were used for interrogations in the Military Criminal Court.