I am wondering for my 2016 return if I should include federal estimated taxes for 2015 paid in 2016 if I already included it on my 2015 return (Form 1040 line 65).

[MinhT · Accepted solution]

The estimated tax payment that you made in January 2016 was the fourth estimated tax payment for tax year 2015 and has already been accounted for on your 2015 tax return.

You cannot use it as an estimated tax payment again on your 2016 tax return.