How do I handle an IRS refund check that clearly belongs to someone else?

Do not treat the check like free cash and do not assume one phone call resolves the account. A mistaken refund often means the IRS posted a payment or credit to the wrong taxpayer account and the automated notice stream has not caught up.

The safest approach is:

1. document why the refund appears wrong
2. follow the IRS return instructions for the check
3. keep copies of everything sent back
4. preserve proof of mailing
5. monitor for follow-up notices while the correction posts

The operational risk is not only the wrong refund itself. The bigger risk is failing to prove that the check was returned and that the taxpayer acted promptly when later letters still show a balance due.