@KuanBABA - while I can't find a specific reference on IRS. GOV, I suspect this is the issue:
the original return is a single filing submission (and this same issue would be true for MFS and HOH as well).
if the 1040X is now submitted electronically changing the filing to a joint return, how do both spouses electronically sign the 1040x return if the original was a single e-signed form?????
and I can't imagine this occurs very often to warrant a prioritized improvement to the software. Simply, your marital status on 12/31/21 determines the MFJ filign status. Didn't Turbo Tax ask you if you were married as part of the interview process?
just curious how you failed to file MFJ in the first place. How did you spouse file? is that being amended as well? or are you really changing from MFS to MSJ?
you'll have to mail the 1040X and expect a 9-12 month wait given the backlogs. Best if the 1040x for both of you are in the same envelope. (meaning spouse has to amend their original filing as well, right?)
this is from the H&R Block website - they state the IRS doesn't permit electronic amendments when there is a filing status change:
https://www.hrblock.com/tax-center/filing/personal-tax-planning/amend-your-return-to-correct-filing-....
