@ShawnMc
It's pretty simple .
amend your 2020 return and report any amount paid back so far (Form 8915-E).
any amount over one third, will be credited to your next tax return. (2021 Form 8915-F).
If you pay it all back in at least thirds within the time frame, there will be no tax.
If you can pay it back all at once now you can handle it all on 2020 amended tax return by not spreading it out.
