I usually use the box 2a value for the box 16 value ...as long as box 2a has a non-zero value (usually the same as box 1)
If I leave box 16 empty on the main screen, and go thru the follow-up page questions, just after the main 1099-R form entries, TTX ends up backfilling box 16 with the value in 2a (at least for my software and NC state).
The only main issue might happen is if box 2a is empty and "Undetermined" is checked nearby.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
