If you see a box 16, you need to put the box 1 $$ in there.......
...or if box 16 isn't displayed, when you edit the 1099-R form, and on a page AFTER the main form, it will ask for the state distribution amount, and you will enter box 1 $$ there again.
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(I usually claim it should be box 2a, as long as 2a has a non-zero real number there...but it is usually the same as box 1 anyhow....but others disagree. If box 2a is blank, or marked "undetermined", then it would be the Federally taxable amount of box 1...if not the same as box 1)
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*