Tax · United States
IRS Notice CP12 — the IRS corrected your return and changed the refund
A CP12 means the IRS corrected mistakes on your tax return and the refund changed as a result. If the correction looks right, nothing needs to be done — the refund arrives on its own; if it looks wrong, a 60-day window exists to object.
How serious: routineAlso called: CP12, math error notice (refund changed), adjusted refund notice
The IRS sends a CP12 when it corrected one or more mistakes on a tax return and the correction changed the refund — a different refund than expected, or a refund where a balance due was expected.
If the correction is right, no response is needed. The refund check arrives in 4-6 weeks, as long as no other tax or debts the IRS is required to collect are owed.
If the correction looks wrong — for example, a credit you were entitled to was removed — there are 60 days to object before the change becomes hard to reverse.
Who sends it
The Internal Revenue Service (IRS) — the United States federal tax authority, part of the Department of the Treasury.
The code 'CP12' is printed in the top corner, with wording like 'We corrected one or more mistakes on your tax return' and a changed refund amount. The notice explains what was corrected and shows the new refund figure.
The deadline
60 days from the date of the notice to dispute the correction: 'If you contact the IRS within 60 days of the date of this notice, they may reverse the change made to your account' (TAS)
There are 60 days from the date printed on the notice to dispute the correction; within that window, the IRS may reverse the change made to the account.
If you do nothing
The corrected amount stands, and a refund check arrives in 4-6 weeks if no other tax or debts are owed. But if the IRS reduced the refund and there is no contact by the date on the notice, the formal right to have the changes reversed is lost, along with the right to appeal to the U.S. Tax Court. After 60 days, changes made to reduce the refund will not be reversed — a formal claim for refund becomes the remaining route.
Compute your date
The rule above is what the law sets. Put in the dates on your own letter and it becomes a date.
Don't miss this date
We'll email you 7, 3 and 1 day before, and on the day — at 9:00 your time.
We keep only what the reminder needs — type, dates, sender — encrypted. Delete it any time.
How it escalates
- 01The corrected refund is paid (in 4-6 weeks) if no other debts are owed.
- 02After 60 days: loss of the right to easy reversal and of pre-payment Tax Court appeal rights.
- 03Any later dispute requires a formal claim for refund with substantiation, generally within 3 years of filing or 2 years of the last payment.
How to respond
Response types
- Confirm receiptNo response (acceptance of the corrected refund)
- File the objectionRequest for abatement / reversal of the math or clerical error adjustment · IRC §6213(b)(2)(A)
- Ask for clarificationClaim for refund after the 60 days (formal refund claim) · IRC §6511Form: Form 1040-X, Amended U.S. Individual Income Tax Return (or Form 843 for certain penalties, interest and fees)
Where and how
- U.S. Mail (First-Class Mail)
- Certified Mail / Registered Mail (USPS), return receipt requested
- Designated Private Delivery Service (DHL Express / FedEx / UPS — qualifying service levels only)
- Fax to the number printed on the notice
- IRS Individual Online Account (irs.gov/account) / Business Tax Account
- Telephone — the number printed on the notice (general line 800-829-1040)
What makes it count
Written responses are timely if postmarked, or given to a designated private delivery service, on or before the date printed on the notice (IRC §7502); certified mail is the safe channel because the 60-day date carries appeal rights. Telephone disputes take effect when recorded by the assistor and faxes on transmission — keep the call reference, assistor ID and fax confirmation, since neither produces a postmark.
Common questions
Does a CP12 require a reply?
Not if the correction is agreed with. The corrected refund arrives in 4-6 weeks, as long as no other tax or debts the IRS is required to collect are owed.
What if the IRS removed a credit I was entitled to?
A 60-day window exists from the notice date: the toll-free number can be called or the IRS written to, and it may reverse the change. After 60 days, a reduction will not be reversed and a formal claim for refund with documentation becomes the route.
When does the corrected refund arrive?
Within 4-6 weeks, unless other tax or debts the IRS is required to collect are owed.
Sources
Facts verified against the sources below on 28 August 2026.