@big_daddy94fu
....If there is an actual $ amount alongside?
THEN the D21, is just a "D".....
..the 21 just indicates that some of the $$ contributed was to pay for some 2021 TSP/401k contributions that were not done during 2021. The "21" isn't entered.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
