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Published:   |   Last Updated: May 16, 2023

Notice CP12

Math Error Resulting in Overpayment

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Notice Overview

The IRS corrected one or more mistakes on your tax return.

A CP12 Notice is sent when the IRS corrects one or more mistakes on your tax return which either result in a different refund amount, or in an overpayment when you thought you owed.

This notice, or letter may include additional topics that have not yet been covered here. Please check back frequently for updates.

What does this mean to me?

The IRS received your individual income tax return; the amount of your refund has now been adjusted. A CP12 Notice is issued when there are mistakes on your return that require correction and an original refund amount is changed.

How did I get here?

You submitted your income tax return with one or more mistakes that needed to be corrected. As a result:

  • The refund amount is different from the one you expected, or
  • You have a refund when you thought you owed money or had an even balance.

What are my next steps?


Review and Compare the notice

Review the notice and compare the IRS changes to the information on your tax return.

To find out what caused your tax return to change, contact the IRS at the toll-free number listed on the top right corner of your notice.

Note: Authorized third parties may assist taxpayers, but the taxpayer must be present on the phone or in-person. Complete and send the IRS a Form 2848, Power of Attorney and Declaration of Representative, to authorize someone (such as an accountant) to contact the IRS on your behalf.


If you Agree

If you agree with the changes the IRS made, no response is required.

  • You should receive a refund check in four to six weeks, if you don’t owe other tax or federal debts the IRS is required to collect.
  • You may want to correct the copy of your tax return that you kept for your records, but do not send it to the IRS.

If you Disagree

If you disagree, contact the IRS at the toll-free number listed on the top right corner of your notice or respond by mail to the address on your notice. If you write to the IRS, include a copy of the notice along with your correspondence or documentation.

If you contact the IRS within 60 days of the date of this notice, they may reverse the change made to your account. You don’t need to provide an explanation or additional documents when you request the reversal, but the IRS will consider any information you provide. However, if you can’t provide additional information that justifies the reversal and the IRS believes the reversal is in error, the IRS will forward your case to the Examination department for a formal review of the items in question. Forwarding your case gives you formal appeal rights, including the right to appeal the IRS decision in court. After the IRS forwards your case, you should be contacted by a member of the Examination staff within five to six weeks to explain the audit process and your rights.

If you don’t contact IRS within the 60-day period, changes made to reduce your refund will not be reversed. Instead, you may file a claim for refund to dispute the changes. Generally, you must submit the claim within 3 years from the date you filed the tax return, or within 2 years from the date of your last payment for this tax, whichever is later.


If you don’t contact the IRS within the 60-day period, you’ll lose your right to appeal their decision before payment of tax. After 60 days, reversal requests must be substantiated.

Where can I get additional help?

Understanding your notice or letter

Get Help topics

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If you still need help

The Taxpayer Advocate Service is an independent organization within the IRS that helps taxpayers and protects taxpayers’ rights. We can offer you help if your tax problem is causing a financial difficulty, you’ve tried and been unable to resolve your issue with the IRS, or you believe an IRS system, process, or procedure just isn’t working as it should. If you qualify for our assistance, which is always free, we will do everything possible to help you.

Visit www.taxpayeradvocate.irs.gov or call 1-877-777-4778.

Low Income Taxpayer Clinics (LITCs) are independent from the IRS and TAS. LITCs represent individuals whose income is below a certain level and who need to resolve tax problems with the IRS. LITCs can represent taxpayers in audits, appeals, and tax collection disputes before the IRS and in court. In addition, LITCs can provide information about taxpayer rights and responsibilities in different languages for individuals who speak English as a second language. Services are offered for free or a small fee. For more information or to find an LITC near you, see the LITC page on the TAS website or Publication 4134, Low Income Taxpayer Clinic List.


Where am I in the tax system?

Math Error Resulting in Overpayment, CP12 Notice