I have already filed my taxes and forgot to include Form 3922 because I sold some stocks in 2016. should I amend? By the way, #14 in my w2 is not blank.

@kb09

IF you used the correct basis to report the sale, which is the sum of your out of pocket cost + the compensation reported by the sale, THEN you don't have to do anything.  You don't really "file" Form 3922; TurboTax uses that information to calculate the correct cost basis if you use the "ESPP step by step" interview.

IF you didn't use the correct basis, reporting only your out of pocket cost, (this is probably what the broker reported to you), THEN you are double reporting your income; once as compensation reported on the W-2 and then again as an overstatement of "gain" on the sale.  In that case you should look into amending if the overstatement of income is significant.

Tom Young