The CP12 means the IRS found a math error or clerical mistake on your return and corrected it. Your refund amount has changed as a result. The notice shows what the IRS changed and what your new refund will be.
Math error authority under IRC Section 6213(b) gives the IRS the power to make certain corrections without going through the full audit process. This is faster for both sides, but it comes with an important catch: you have only 60 days to dispute the correction.
What "Math Errors" the IRS Can Correct
The IRS's math error authority extends beyond simple arithmetic. They can correct actual math mistakes on the return, entries that don't match supporting forms or schedules, Social Security numbers that don't match SSA records, entries that exceed statutory limits (like excess contributions), and omissions of required information.
This means the IRS can make substantive changes to your return under the "math error" banner. A disallowed credit because the IRS's records show a different income amount is technically a math error correction, not an audit. That distinction matters because your rights are different.
The 60-Day Rule
You have 60 days from the date of the CP12 to request abatement of the math error assessment. If you request abatement within 60 days, the IRS must reverse the correction and follow the normal deficiency procedures (which give you more rights, including access to Tax Court).
If you don't request abatement within 60 days, the correction becomes final. You can still file an amended return, but you lose the procedural protections that come with the formal deficiency process.
What to Do
Compare the IRS's correction to your original return. If they're right, no action needed. Your adjusted refund will be processed. If they're wrong, write to the IRS within 60 days requesting abatement of the math error. Explain why the original entry was correct and include supporting documentation.
Most CP12 corrections are legitimate. The IRS caught a genuine error and fixed it. But if they changed something that was correct on your return, don't let the 60-day window close without disputing it.
Questions about a CP12? Call us at (813) 229-7100.