H has filed 2018 return as MFS. W has not filed and wants to file MFJ with H. Is amended return required or just return reporting both income

[user0609261623]

H filed timely MFS return. W has not filed and wants to file MFJ with H.  Is last return filed before due date considered original return in lieu of filing 1040X?

[JohnW15]

If you both agree to file jointly, then you'll have to amend your husband's return. 

The IRS can't have the original MFS return hanging out there in your husband's name, then have an MFJ return come in on your name.  They'd have to contact you both, and you'd spend weeks (at least) sorting out the mess.

Please see the TurboTax FAQ "How to amend (change or correct) a return you already filed," below, for instruction on how to amend your husband's previously-filed tax return.

https://ttlc.intuit.com/replies/3288565