Changing from filing joint to filing separate, and vice versa

If you're changing from married filing joint to married filing separately, you and your spouse may file separate returns before the due date of the original return even if you already filed a joint return for the tax year.

If you're changing from married filing separately to married filing joint, pay the total tax shown on the joint return at or before filing the joint return. You will be entitled to a refund if you previously paid more than the corrected amount.

Changing to a joint return after filing a separate return must be made on an abatement/amended return within 3 years after you last filed a separate return. This period is determined without taking time extensions granted to either spouse into account.