What Is an IRS CP12 Notice?

Q: Will CP12 delay my refund?

It can. CP12 explains the new amount and if an offset applies. Monitor status until issued or applied to other debts.

Q: Should I amend my return after a CP12?

Not usually. CP12 reflects an IRS math correction. If you believe it is incorrect, respond with documentation; an amended return can be strategic in limited cases.

IRS Notices Explained
Written by Enrolled Agent
Reviewed by Enrolled Agent

A CP12 means the IRS corrected a math error on your return and adjusted your refund. Here’s why you received it, what changed, and how to make sure your refund is correct.

Quick Answer

The IRS found a math error and changed your return. Your refund amount was adjusted (increased or reduced), or a balance may have been created/applied to other taxes. The CP12 shows what changed and your new amount.

Important: If you disagree, respond by the deadline on your notice. If you agree, no action is required unless the CP12 instructs you to provide additional information.

Why You Received a CP12

Arithmetic or computation errors on your return (credits, deductions, taxable income).
Incorrect credit calculations (e.g., child-related credits, recovery credits).
Withholding or estimated payment amounts didn’t compute correctly.

CP12 differs from CP11: CP11 results in a balance due; CP12 results in a refund adjustment.

What the CP12 Means

The IRS recalculated part of your return. The notice lists the corrected figures and your new refund or balance. It may also explain if your refund will be offset to other federal or state debts.

Review the line items the IRS changed and verify them against your filed return and documents (W-2, 1099, schedules).

What to Do Next

Match your next step to your situation:

If you agree: Keep the notice with your records. Track your refund status; if offset is mentioned, expect adjustments.
If you disagree (fully or partially): Contact the IRS by the date on your notice. Provide documents (W-2/1099, schedules, worksheets) that support your original figures.
If you’re unsure: Pull IRS transcripts and compare them to your filed return and the CP12 changes.

Need the bigger picture? Start with our
IRS Notice Help Center and
Complete Guide to Back Taxes.

If You Ignore the CP12

If you disagree and do nothing, the IRS will treat the change as final. If the CP12 created an offset or reduced refund and you believe it’s wrong, delays in responding reduce your options to correct it.

Timely responses preserve rights and help prevent follow-up notices or incorrect balances.

How Polaris Can Help

Polaris Tax & Accounting helps taxpayers nationwide review CP12 adjustments. Our Enrolled Agents reconcile the IRS math against your return and transcripts, correct errors, and protect refunds. If needed, we communicate with the IRS on your behalf.

You get clarity, documentation, and a clean path forward.

Your Next Step: Have an expert confirm your CP12 is correct.
Schedule a consultation.

Related Resources

FAQs

How is CP12 different from CP11?

CP12 adjusts your refund due to a math error. CP11 finds a math error that creates a balance due.

Will CP12 delay my refund?

It can. The notice explains the new amount and whether an offset applies. Monitor status until paid or applied.

Should I amend my return after a CP12?

Not usually. CP12 reflects an IRS math correction. If the change is wrong, respond with documentation; an amended return can be strategic in limited cases.