After you file

in 2024;  these instructions don't work.  In  1040, deductions and credits there is no Other Income taxes.

 

I guessed by going to Estimated taxes paid,  the first choice.  Then:  Federal taxes (and state taxes) then AT the bottom:  Additional payments.  Entered the date I'll mail my extension.

 

== this is too much work for filing an extension with a check for the tax balance.  Once upon a time TT was helpful and when you filled out fornm 4868 or teh state extesion and you entered the amount paid it updated the taxes due automatically.  Instead in 2024 I had to google, search here, poke around, wasting time.  It could have been automated within TT, like I';m paying for...  :(