with a copy of the check in front of you - you'll need a copy of the front and back - you can try calling the IRS
800-829-1040
First choose your language.
Then 2
Then 1
Then 3
Then 2
When asked for SSN do nothing it will ask twice
Then 2
Then 4
You should then be transferred to an agent, but there is likely to be a long wait. if the agent can trace the check from the info the IRS puts on the check, you shouldn't have to do anything further. If the agent can't trace it or maybe doesn't want to, they'll tell you to send back the notice with a copy of the check.
or you can send back the notice with a copy of the front and back of the check. use a method where you get proof of delivery
sometimes taxpayers do not put enough info or put incorrect info on their check. there is also the possibility the agent entering the payment in the IRS computers made a mistake. then the IRS does not give taxpayers credit. The IRS is holding millions in unapplied funds. there is another possibility. there's an error on your return but that should show up in the notice.
