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You generally make this choice when you file your joint
return. However, you can also make the choice by filing
Form 1040-X, Amended U.S. Individual Income Tax Return.

Attach Form 1040 or 1040-SR and enter “Amended”
across the top of the corrected return. If you make the
choice with an amended return, you and your spouse
must also amend any returns that you may have filed after
the year for which you made the choice.