"If you will change from MFS to a joint return with a spouse who has already filed then the spouse's filed return must be AMENDED not superceded."
The idea of a superceding return is to replace the original return with another original return filed before the due date. Indeed, the regulations quoted earlier here seem to state that all amended returns filed before the due date must be processed as a superceding return anyway. With respect to a MFJ superceding a MFS, does it perhaps matter which name is listed first?
"Amending the spouse return to add you WILL report a return filed in your name ... why ever would you think it would not ?"
Because it doesn't and I've already been in that pickle in tax year 2017. Amended returns are not authorized by Congress. All IRS can do with them is perform account adjustments to issue refunds or send bills, etc. The Tax Court refers to IRS acceptance of amended returns as, "an act of administrative grace." Superceding returns, on the other hand, are considered a totally different situation. When a MFJ amended return is received where only one spouse filed a MFS, what they actually do is copy the one MFS return, as originally filed, to be the original filing for the other spouse too, then perform the usual amended return account adjustments. While that happens to also achieve my student loan forgiveness eligibility goal here, it does create some major confusions for third parties if you need to use tax return filings to prove annual income, so I don't suggest it. It also takes IRS a long time to process, as you mentioned, since amended returns are a manual process while original filings are rather automated.
