Did you read my post above? And the IRS will mail you a letter saying why. I bet they reduced the penalty on line 38. I don't have problems doing 2210. It's easier if you use the Desktop program. And you can select to leave the penalty off and have the IRS figure it for you.
And as for making a 4th qtr estimate, you can wait until you know the extra income amount. The 4th qtr isn't due until Jan 15.
