I'm not in safe harbor for estimated taxes and I had an unexpected capital gain in December and made an estimated payment to "cover it" in December. What do I do in TurboTax to tell the IRS that I didn't under-withhold during the first three quarters, that the extra income was realized in the fourth quarter, and I shouldn't have a late payment penalty, since I didn't know about the capital gain when I made the first three payments?
