CP12· Math-error correction
CP12 — Math-error correction with refund change
- Category
- Math error
- Urgency
- Informational
- Response window
- see notice
- Key form
- —
No action required — retain it with your records.
Why the IRS sent this
IRS-detected math / processing error that resulted in a refund or refund adjustment.
Response window
The IRS detail page for CP12 does not state a fixed day count. The response-by date is printed on your individual notice — read the date at the top-right corner.
What to do
Required action
Review the corrections. If you agree, no response is required. If you disagree, contact the IRS by the date shown on the notice.
Appeal path
Informal — call the IRS
Informal dispute via the toll-free number. The U.S. Tax Court is referenced for formal appeal rights, exercisable before the deadline.
Notes from the primary source
Covers CP12, CP12E, CP12F, CP12G, CP12N, and CP12U variants. Statutory 60-day abatement-request window under IRC §6213(b) is NOT restated on the detail page.
Calm-corrective
Only the IRS can resolve your notice
We are not a CPA firm, not a law firm, not an Enrolled Agent firm, and not affiliated with the IRS. We don't accept payments on your behalf, settle your debt, or call the IRS for you. What we do: explain what your notice means, point you to the right IRS form, cite the statute that authorizes the action, and surface the appeal path. Then you call the number on the notice, file the form, or hire a licensed professional.
Related notices
Likely next or sibling codes
- CP11The IRS corrected one or more math or processing errors on your return, and the change resulted…
- CP23The IRS adjusted your return because estimated-tax payments reported on the return did not match…
- CP49Notification that all or part of your refund was applied to a tax debt owed by you or your spouse.
Source
Verified against the official IRS detail page on irs.gov/individuals/understanding-your-cp12-notice. Always re-verify against the IRS page before acting.