The first move
Note the date on the notice and the 60-day window. If you disagree, write within it. After 60 days you owe the tax and must pay before you can dispute.
What these letters have in common
Math error authority lets the IRS correct arithmetic, a missing form, a credit claimed with a wrong Social Security number, or a figure that contradicts its records, without an examination. The notice tells you what changed. CP11 means you now owe. CP12 means your refund changed. CP13 means no change to the tax. CP21 and CP22 report changes you requested (an amended return) or the IRS made.
The 60-day rule is the important part. If you ask for the change to be reversed within 60 days of the notice, the IRS must reverse it and, if it still disagrees, go through normal deficiency procedures, which preserves your right to Tax Court before paying. Let the 60 days pass and the assessment stands.
Most math error corrections are correct. Check the notice against your return before deciding.
What to gather
- The notice, with the explanation of the change
- Your return as filed, with the schedule or form the notice references
- Documents supporting the figure you reported (the W-2, the 1099, the dependent's Social Security card)
- Your amended return, if the notice is a CP21 or CP22
How to write back
- CP14 response letter: A short letter that responds to a balance due notice: what you are paying, what you dispute, and what you are attaching.
Notices in this family
| Notice | What it means |
|---|---|
| CP10 | The IRS changed your return and reduced the amount applied to next year's estimated tax |
| CP10A | Same as CP10, related to the earned income credit |
| CP11 | Math error correction, balance due |
| CP11A | Math error correction involving the earned income credit, balance due |
| CP12 | Math error correction, refund changed |
| CP12A | Refund changed, earned income credit |
| CP12E | Refund changed, other correction |
| CP12F | Refund changed, specific credit correction |
| CP12G | Refund changed, credit correction |
| CP12N | Refund changed, no additional action |
| CP12U | Refund changed, unpostable correction |
| CP13 | Return corrected, no change to tax owed or refund |
| CP13A | Return corrected involving the earned income credit, no change to balance |
| CP13M | Return corrected, no change, credit related |
| CP21A | Changes you requested were made, balance due |
| CP21B | Changes you requested were made, refund due |
| CP21C | Changes you requested were made, no balance change |
| CP21E | Changes from an examination, balance due |
| CP21H | Changes related to an obsolete provision |
| CP21I | Changes related to an IRA issue, balance due |
| CP22A | Changes you requested were made, balance due |
| CP22E | Changes from an examination, balance due |
| CP22H | Changes related to an obsolete provision |
| CP22I | Changes related to an IRA issue |
| CP23 | Estimated payments claimed do not match IRS records, balance due |
| CP24 | Estimated payments claimed do not match IRS records, refund due |
| CP25 | Estimated payments claimed do not match IRS records, no balance change |
| CP101 to CP107 | Business return math error corrections, balance due |
| CP111 to CP117 | Business return math error corrections, refund due |
| CP123 to CP127 | Business return math error corrections, no balance change |
| CP131 to CP133 | Business return corrections with credit adjustments |
| CP210 | Business: changes made to your return, balance due or refund |
| CP220 | Business: changes made to your return, balance due |
When to get help
If the correction removed a credit worth thousands (EITC, child tax credit, education credits) and you believe you qualify, respond in writing within 60 days and consider help.
Before you send anything
This is general information, not tax advice. Situations differ. Check with your tax advisor before you send anything. Nothing on this page creates a client relationship.