Your 2021 Federal tax refund was reduced because you claimed a dependent / qualifying child / qualifying relative
- that was claimed by another taxpayer, or
- for which you were not eligible to claim.
Hopefully, the communication from the IRS is clear about the issue and what steps you need to take to resolve the issue.
If another taxpayer is claiming the same dependent / qualifying child / qualifying relative, and you believe that you are justified in claiming this dependent / qualifying child / qualifying relative, you may submit an amended 2021 Federal 1040 tax return and claim the individual.
Submit the amended tax return by US mail. At some point, the IRS will contact you and require you to prove your claim to the dependent / qualifying child / qualifying relative.