I forgot to file one of the 1099-B I received

[mablair2]

However, I would get additional money back if I file an amendment, so I need to file the amendment?

[jerry2000 · Accepted solution]

Yes, you do, for two reasons. The first reason is that you will get more money back. The second reason is that the IRS gets a copy of your 1099-B, and if you don't report it on your tax return, the IRS will assume that the entire gross proceeds are profit and they will send you a bill for additional tax, plus penalties and interest for failure to report and failure to pay. You can avoid that unpleasantness by amending your return and reporting the 1099-B.

[BethanyJ]

Yes you will need to file an amendment.