We're married and filing a joint return. How do we use/enter the IP PIN if 'one' or 'both' of us have one

If you are married and filing a joint return, and one or both of you have been issued an Identity Protection Personal Identification Number (IP PIN) by the IRS, you must enter each IP PIN on your tax return. Specifically, each taxpayer who has an IP PIN must enter their respective IP PIN in the designated spaces on the tax form.

For electronic filing, the return must include the IP PINs for both spouses if both have been issued one. The IP PINs should be entered in the spaces provided next to the space for your occupation or next to your daytime phone number, depending on the form instructions. If only one spouse has an IP PIN, only that spouse's IP PIN needs to be entered.

If you do not enter the required IP PIN(s), your electronic return will not be considered validly signed and may be rejected. If you encounter a rejection due to a missing IP PIN, you will need to retrieve the necessary IP PIN and resubmit your return.

In summary:

1. Each spouse with an IP PIN must enter their IP PIN on the tax return.
2. Enter the IP PINs in the designated spaces on the form.
3. Ensure all six digits of each IP PIN are correctly entered.
4. If the return is rejected due to a missing IP PIN, retrieve the necessary IP PIN and resubmit the return.

Sources:
Publication 17 (2023)
Instructions for Form 1040-SS (2023)
Publication 535 (2022)
Publication 1380
Publication 4801 (2/2024)