@findchris
When you amend the only form you have to attach to your 1040-X is Form 8915-E ( not the revised 1040 ).
It should show on Line 10 an amount paid back of $100,000. That will match your form 5498 sent later.
This results in an "amount subject to tax in 2020" of zero.
You can't expect all your withholding back.
You only get back the tax you paid on $33,333.
The rest of what you paid back 66,667 is applicable to your 2021 tax return,
Form 8915-F Line 14, which you will have to enter yourself,
and which also results in an "amount subject to tax in 2021" of zero. see worksheet 3.
