Thanks for the quick response but I'm still a bit confused. On one hand, you are confirming we are not subject to estimated taxes because we are married filing jointly and taxes are being paid via my W2. On the other hand, you are saying we should pay them and missed the filing deadline. I guess I'm trying to differentiate between "should" and "must". So if I just use the online payment tools the IRS offers, pick "estimated taxes" as the reason (I've look at all them and I don't see a "just feel like paying early" option), and send them a few thousand bucks, will the IRS know I've already been paying taxes and am prepaying 2021 vs the estimated tax for which I missed the deadline? I know, I'm trying to be super specific here.
