A couple of weeks ago I said I was going to take my underpayment penalty of $10 and not file the 2210. So, of course, given the update this morning I've got to take another try at AI on Form 2210. I got the same $10 penalty. Actually, that makes perfect sense given I underpaid my 2021 liability after I account for the 2020 overpayment applied to 2021, estimated payments and my withholding. Line 33 of my 1040-SR is accurate to the penny; therefore, I'll pay the $10 penalty and conclude it is what it is.
What's more troubling about this (fantastic) thread is that we're about one-third of the way through the month of March and we don't have confidence in the TT application. If this were January, I wouldn't be posting this input. But we're in March and I'm reading suggestions about "work arounds" to account for the 2020 refund by essentially adding a fifth estimated payment. I applaud @Tax4fp but we just shouldn't have to be doing this when we're a little over five weeks away from filing. This is the time of tax filing season when I'm simply waiting for corrected 1099's from my brokerage, not waiting for the next TT update.
