After you file

To use TurboTax to file an amended 2021 return, you would need to purchase TurboTax 2021.

You would need to upload the original tax file or enter everything the way you originally filed. 

If you need to make a new "Mock" 2021 return in the TurboTax software, you would indicate that you will mail the return in so the program thinks you filed and therefore will allow an amended return to be generated. 

HERE is a link for TurboTax 2021

HERE is a link about using TurboTax to amend your return

On the amended return, since you wish to change to Married Filing Jointly, you will need to include all the income of you both. 

You need to include a statement electing that choice. 

The newer programs will generate the statement for you, but the older versions do not.

This election must be made by you both, and both sign the statement.

• For the first year you want to file an election to have the spouse treated as a resident for tax purposes, you must file MFJ
• The first year filing MFJ, inform the IRS of your election.
• Spouse is taxed as Resident for tax filing purposes
• Report all worldwide income, including all foreign income.
• May be allowed a Foreign Tax Credit or the Foreign Earned Income Exclusion (FEIE).

Election is valid until suspended or revoked

Once revoked, the election is no longer available to that non-resident alien

If your spouse has an ITIN, use that number, if not, use 999-88-9999 to get through the program, but be sure to white that number out when you print the amended return (Form 1040X)

Enter worldwide income for both spouses
Select “Foreign Taxes” under “Deductions and Credits” “Estimates and Other Taxes Paid”
Continue through the interview for the credit or deduction if applicable
Select “File by Mail” and print the amended return
Both sign a statement electing to both be treated as residents for tax filing purposes 
IF ITIN used, mail tax return and statement to address indicated on TurboTax instruction sheet

IF NO ITIN, white-out the mock SS#, include W-7 Mail package to the address indicated on W-7 instructions (Austin, TX)

HERE is a link about for applying for an ITIN 

HERE is more about making the election