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CP12 key facts
| Official name | We corrected one or more mistakes on your tax return. As a result, you are now either due a refund or your original refund amount has changed. (Includes CP12, CP12E, CP12F, CP12G, CP12N and CP12U; IRM title: Overpaid Math Error - Refund Due) |
|---|---|
| Who gets it | Individuals |
| Severity | 2 of 5: Low: check it and respond if asked Nothing is owed and a refund is generally coming, but the math-error dispute window ends formal reversal rights if you disagree with a reduced refund. |
| Response window | No response is needed if you agree. If you disagree, contact the IRS at the number on the notice by the date indicated. Under IRC 6213(b)(2)(A), as described in IRM 21.5.4.3, a taxpayer has 60 days from the date of a math error notice to request abatement. |
| Deadline basis | The date printed on the notice. |
Severity is RAHA Financials' own 1 to 5 rating of how urgent the notice usually is. It is not an IRS classification.
How long do I have to respond to a CP12?
Use the date printed on your notice. It is typically 60 days from the notice date. Enter the notice date to see an approximate date.
The date printed on your notice always controls. Open CP12 in the IRS Notice Decoder.
Why did I get a CP12?
Common reasons include:
- A calculation error on the return
- A credit amount the IRS adjusted during processing
- A mismatch between the payments or withholding claimed and the IRS's records
- Figures transferred incorrectly between forms or schedules
What should I do?
- Read the notice section that explains what the IRS changed on your return.
- Check the change against your copy of the return and your records.
- If you agree, no response is needed; the IRS says a refund generally arrives within 4 to 6 weeks if you don't owe other taxes or debts it must collect.
- Correct your own copy of the return for your records, but don't send it to the IRS.
- If you disagree, call the number on the notice before the date shown, with your return and documents at hand.
What documents do I need?
- The CP12 notice
- Your copy of the tax return
- W-2s, 1099s and any credit worksheets related to the changed line
- Records of estimated or other payments made for that year
What should I avoid?
- Don't wait past the date on the notice if you think the change is wrong.
- Don't mail in a corrected copy of your return; keep it for your records.
- Don't assume the refund on your original return is the amount you'll receive.
What if I disagree with a CP12?
Contact the IRS at the number on the notice by the date indicated. Per the IRS page, if you miss that date you lose formal rights to have the change reversed and your right to appeal to the U.S. Tax Court. The statutory window to request abatement of a math error is 60 days from the notice date (IRC 6213(b)(2)(A), IRM 21.5.4.3). Later corrections generally require Form 1040-X or another claim.
What happens if I ignore a CP12?
If you agree, ignoring it is generally fine and the adjusted refund should be issued. If you disagree and don't contact the IRS by the deadline, the change generally stands and you lose the formal right to have it reversed or to appeal it to the U.S. Tax Court.
What else should I know about CP12?
Even though a CP12 usually comes with a refund, it is still a math error notice, so the 60-day window in IRC 6213(b)(2)(A) (IRM 21.5.4.3) is the time to challenge the change. People often skip it because they are still getting money back, but if the IRS lowered a credit or refund and you don't contact them by the date shown, you lose the formal route to reverse it and to go to Tax Court. The notice also comes in lettered versions (CP12E, F, G, N, U) that the IRS page covers together.
Want a professional to handle your CP12 response?
IRS Notice Response Plan
Fixed price, quoted before any work startsFixed fee.
- Review of your notice and account transcript
- A written plan: agree, partly agree, or dispute
- Draft response and list of supporting documents
- Deadline tracking so nothing lapses
CP12: frequently asked questions
Do I need to respond if I agree?
No. The IRS says no response is required, and you should get your refund within 4 to 6 weeks as long as you don't owe other taxes or debts it is required to collect.
How do I find out what caused the change?
Review the section of the notice that explains what was changed on your return, or call the number on the notice.
What happens if I miss the date on the notice?
The IRS says you lose formal rights to have the change reversed and your right to appeal to the U.S. Tax Court.
My refund still hasn't arrived after the notice. Why?
The IRS notes the 4 to 6 week timeframe assumes you don't owe other taxes or debts it must collect; if you do, part or all of the refund may be applied to those.