In the past 2 weeks I have received about a dozen letters from IRS denying extensions of time to file, claiming they weren't filed on time. For 1040s, 1041s and 1120s.

I'm about to argue my first one. Just efiled a 1041 and the trust owed.

I'm not doing anything about the others yet. If they don't owe, no problem. If they do, I'll fight.