IRS CP12 notice: the IRS corrected your return and changed your refund

What does the IRS CP12 notice mean?

The IRS CP12 is a math error notice for returns that still end in a refund. When the IRS processed your return, it found something it could fix on its own, such as an arithmetic mistake, a figure carried to the wrong line or a credit that did not match the rules or the information it holds. It made the change, recalculated the refund and mailed you this notice.

A CP12 is not an audit and not a bill. It tells you the new refund amount and lists each correction. The IRS also sends a CP12 when a change increases a refund, or creates one where the return showed none, so a CP12 is not always bad news.

The notice code is printed in the top right corner of the page. If the code reads CP11 instead, the corrections produced a balance due rather than a smaller refund; see the IRS CP11 notice. If it reads CP13, the changes left your balance at zero.

Common corrections behind a CP12

The notice names the specific change. These are the kinds of corrections that most often show up on a CP12:

Estimated payments are a frequent mismatch. If you paid in the wrong tax year, or paid under your spouse's SSN on a separate return, the IRS will not see the payment where you claimed it and will reduce the credit.

If you agree with the CP12

You do not need to reply. Correct the copy of the return you keep for your records so next year's figures start from the right numbers, and tell your preparer if one was involved. Do not mail a corrected return to the IRS and do not file Form 1040-X for a change the IRS already made.

The IRS says to expect the corrected refund within 4 to 6 weeks of the notice, as long as you do not owe other federal tax or debts. If you do, part or all of it can still be taken; see tax refund offset.

How to dispute a CP12 notice

If you think the IRS got it wrong, contact the IRS by the date on the notice. That date is generally 60 days from the notice date. Responding in time keeps your right to have the change reversed and, if needed, to appeal to the US Tax Court.

1. Find the exact line the notice says was changed and compare it with your return and your source documents.
2. Gather proof for your original figure: W-2s, 1099s, credit forms, payment confirmations or dependent records.
3. Call the toll-free number printed in the section of the notice about where to find more information. The IRS says phone is the fastest way to resolve many return errors.
4. Ask whether you can fax documents during the call. The IRS allows this for CP12 disputes.
5. Write down the date, the representative's ID number and what was agreed.
6. Watch for a follow-up notice showing the reversal and the new refund amount.

The IRS says most refund reductions can be reversed without documents if your original entry was right, but supporting records speed things up. If you miss the date, the IRS may still consider your information, but you lose the formal rights tied to the deadline.

IRS CP12 phone number and how to verify the notice

Use the number printed on your own notice rather than a number from a search result. To confirm a letter is genuine, sign in to your IRS Individual Online Account and check the notices section, or compare the notice with the sample on the IRS page for CP12 at irs.gov.

CP12 refund timing and what shows on your transcript

After a CP12, Where's My Refund may show the corrected amount or a message about a change. Your account transcript is more exact. A math error adjustment usually posts with a code such as TC 290, and the refund itself posts as TC 846 with the date it was issued. Our page on transcript code 290 explains that entry.

If more than 6 weeks pass after the notice date with no deposit and no offset letter, see tax refund not received for how to ask the IRS to trace it.

Preventing another CP12 next season

Most CP12 corrections come from a handful of entry mistakes, so a few checks before you file in the 2027 season prevent most of them. Enter withholding from each form separately, match estimated payments to your IRS online account payment history, and attach every form a credit requires. The IRS also suggests e-filing, because software catches many arithmetic errors that paper returns carry through.

For a broader look at reasons a refund comes in under your estimate, see why is my tax refund so low.