If you're asking about TIFR GS (Tata Institute of Fundamental Research) then the last date to fill application form has already been passed and even the results have been declared for the same. Have a look at the important dates, here you go-
Release of Application form- 4th January, 2021
Last date to fill application form- 1st February, 2021
Release of Admit Card- 24th February, 2021
Conduction of Result and interview- 18th March, 2021
Final selection List- To be announced
Wait for the next year to fill up the form for TIFR.