If the tax amount involved was more like $3,000, not $300, I would probably file the amended return. (We have the same situation with the state return.) But I think I’ll just try to attach an explanation to the 2021 return, explaining the change in credit carryover amount.

Sometimes IRS surprises me, with the data they roll over from year to year. Don’t they track how many years the AOC credit has been claimed? Or maybe that’s just the software. And then there are the people who are still paying back the new home credit from a generation or so ago. Just when the last of those are gone, they’re talking about bringing it back.