IRS Notice CP11: Math error — you now owe
Quick answerThe IRS found a miscalculation on your return and corrected it. The correction means you owe money (or more than you thought).
Letter / noticeCP11
MeaningMath error — you now owe
Action needed?Yes — see steps
What happens next
You generally have 60 days to dispute the change.
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What you should do
- Compare the IRS correction to your return
- Pay by the due date if you agree
- Call or write within 60 days if you disagree
Scam check: the IRS first contacts you by mail. Use only the phone numbers printed on your letter or on IRS.gov — never ones from a text, email or unofficial site.
Frequently asked questions
What does IRS Notice CP11 mean?
The IRS found a miscalculation on your return and corrected it. The correction means you owe money (or more than you thought).
What should I do?
Compare the IRS correction to your return Pay by the due date if you agree Call or write within 60 days if you disagree
How long does it take?
You generally have 60 days to dispute the change.
Sources
- IRS: Understanding your IRS notice or letter
- IRS: Get Transcript
- Taxpayer Advocate Service (independent help inside the IRS)
Written by the editorial team and checked against the official sources above. See our editorial policy.
By the TranscriptCodes Editorial Team · Last reviewed 2026-11-12.