IRS / Tax Error Code

CP11 | Math error notice (changes to return)

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IRS / Tax

Canonical

/irs-tax/error-codes/cp11-notice/

Last Updated

Apr 16, 2026

Summary

CP11 is an IRS notice indicating the IRS changed your return due to a math or other processing error, often resulting in a balance due.

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What This Code Means

CP11 is an IRS notice indicating the IRS changed your return due to a math or other processing error, often resulting in a balance due.

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