Other Features of the 2020 Recovery Rebates SSN Requirement: Taxpayers must provide a Social Security number (SSN) for themselves, their spouse (if married filing jointly), and any child for whom they claim the $500 child credit. Adoption taxpayer ID numbers (ATINs) are also acceptable for adopted children. Taxpayers who provide an individual taxpayer identification number (ITIN) are ineligible for the credit. Hence, married couples in which one spouse has an SSN and another has an ITIN are generally ineligible for the credit. The law relaxes these ID requirements for married joint filers in which at least one spouse is a member of the Armed Forces. In those cases, only one spouse must provide an SSN.
This is the rule feature, there is a bug or Gap for those who filed 2019 with one SSN and one itin but received the SSN in 2020. No idea how IRS will handle this.
