Deductions & credits

To claim the Child Tax Credit on a 2023 tax return, the taxpayer (and spouse if filing jointly) must have a Social Security Number (SSN) or individual taxpayer identification number (ITIN) by the tax filing due date of the return (including extensions). Any child used to claim the Child Tax Credit or the Additional Child Tax Credit must also have an SSN valid for employment issued by the due date of the return (including extensions).

To claim the Earned Income Credit (EIC) on a 2023 return, the taxpayer (and spouse if filing jointly) must have a valid Social Security Number (SSN) by the due date of the return (including extensions). Any qualifying child listed on Schedule EIC (Form 1040) must also have a valid SSN. Adoption and individual tax payer identification numbers (ATINs and ITINs) do not qualify. The SSN is not valid if the Social Security card states “Not valid for employment.” If the Social Security card states “Valid for work only with INS authorization” or “Valid for work only with DNS authorization,” the SSN is valid for EIC, but only if the authorization is still valid.

So, the first hurdle to pass is whether you had a valid Social Security Number by the due date of the return (including extensions), or a valid ITIN number by the due date of the return (including extensions). If you had an ITIN, not a SSN, then your tax return would not qualify for the Earned Income Credit, but could still qualify for the Child Tax Credit.

The second hurdle is whether your son had a valid Social Security Number by the due date of the return (including extensions).  If you child did not have a valid social security number by the due date of the return, then they would not qualify for the Child Tax Credit or Earned Income Credit.

You mentioned that you applied for the SSN for your child on 4-10-23, and that your child received a SSN about a month later. Is the SSN issued to your child "valid for employment, or does it indicate is it NOT valid for employment?

Assuming you have a valid SSN or ITIN, and assuming your child received a valid SSN in May, the next step is the hurdle that you must have had those by the due date of the return, INCLUDING EXTENSIONS.  If you filed for an extension for your tax return, received the SSN or ITIN numbers and then subsequently filed your return before the extended due date, then you meet this rule. If, however, you did NOT file an extension, then you would not be eligible for the Child Tax Credit or the Earned Income Credit if your child received the SSN after the original un-extended due date of the return..

Given the timeline you presented, I would suspect that the IRS does not have all the information needed for these credits, especially if you filed immediately after you received your child's SSN. The letter you received from the IRS should have an option to disagree with the letter and to send a response back to the IRS.  You would want to follow the process in the letter, and send documentation proving that you filed a valid extension, proving the date you received your ITIN or SSN, proving the date your son received his SSN, proving his SSN is "valid for employment" and proving that you filed your tax return AFTER those dates, but before the extended due date of the return.