If I need to amend my taxes to file jointly, instead of separately, but my wife has not filed yet, can she just file, to null my filing, or do I still need to amend mine?

[WillK]

You will need to amend yours to show that you are married filing jointly, and add your wife's information on the amended return. When you file as married filing jointly, both you and your spouses information and income are on the same return. 

. You should not try to amend your return until the original return it has been fully processed and you have received your refund or your payment has cleared.
Amended returns do not “catch up” to your original return and replace them; they are processed as two separate returns.  
Amended returns have to be printed and filed by mail.  It can take the IRS up to 12 weeks or longer to process them.   If you are due a larger refund than on your original return, your amended return should only show the difference and you will receive a separate check for it.  If you owe money on your amended return, it will show only the new amount owed, you will have to mail a check with the return. Click here for amending instructions: https://ttlc.intuit.com/replies/3288565

[abby-chandler]

How does this effect the spouse who did not file?

[MelissaWilkinson]

Me and my husband already filed but need to do aminded one and file together

[DonnaLO]

How do I amend my 2019 TurboTax Online return?