@Topangamama
"how much of my remaining excess contribution I would like to credit towards my 2021 IRA"
an excess contribution cannot be credited toward your 2021 IRA.
it is your allowed contribution this year that can be applied to reduce the some or all of the excess.
After that, maybe you have allowed contribution left and you can make a reduced 2021 IRA contribution.
the calculation must be down twice if you and your spouse both had an excess contribution.
