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IRS notice decoder · Corrections the IRS made

CP11: the IRS corrected your return and you owe

A CP11 says the IRS fixed a mistake on your return and now you owe. Check the change, then pay or disagree by the date on it.

By the Carry Forward Learning team Reviewed by Hunter Nottingham, JD, CPA

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CheckedOct 19, 2026

What a CP11 means

A CP11 means the IRS corrected one or more mistakes on your return, and the correction left you owing money. The notice shows what changed and how it affected the balance. source 1

Under federal law, a math or clerical error notice isn't a notice of deficiency. The IRS can assess the corrected tax right away, and you can ask it to abate that assessment within a set period after the notice. If you ask in time, the IRS must abate it, and any reassessment has to go through the normal deficiency process. source 2

We treat a CP11 like a short exam: find the line the IRS changed, decide who's right, and act before the date.

The date that counts

Pay by the date on your notice to avoid more penalties and interest. If you disagree, contact the IRS at the number on the notice by the date shown on it. If you don't contact the IRS by the date on the notice, the IRS says you lose formal rights to have the changes reversed and your right to appeal to the Tax Court. Documents sent later are still considered, and the IRS may reverse the change if it agrees. source 1

Why people get one

  • A number was carried wrong between forms or schedules.
  • A credit or deduction was claimed that the IRS couldn't match to its records or the return's own figures.
  • A simple arithmetic mistake changed the tax.

First steps

  1. Read the section of the notice that lists what the IRS changed, and find that line on your return. source 1
  2. Check your IRS online account, typed in yourself at irs.gov, to see the notice and your balance or payments.
  3. If you agree, pay by the date on the notice, or set up a payment plan if you can't pay it all. Correct your own copy of the return, but don't send it to the IRS. source 1
  4. If you disagree, call the number printed on your notice by the date shown. The IRS says it generally reverses changes that increased what you owe, and you don't have to send documents, though they can speed things up. source 1
  5. Keep the notice and a note of who you spoke with and when.

What not to do

  • Don't let the date pass if you disagree. That's when the formal right to a reversal ends. source 1
  • Don't pay or send documents through a link or phone number in an unexpected email or text. Use irs.gov, typed in yourself.
  • Don't mail in a corrected copy of the return as your answer. The IRS says to keep it for your records. source 1
  • Related CP12 A correction that changes a refund or creates one.
  • Related CP13 A correction that leaves the account at zero.
  • Related CP10 A correction that changes the estimated tax carried to next year.

Keep reading

Questions

What if I disagree with a CP11?

Contact the IRS by the date on the notice. The IRS says it will generally reverse changes that increased the amount you owe or affected a refund request. source 1

Will I be charged interest on a CP11 balance?

Yes, if you don't pay in full by the due date on the notice. source 1

Can a CP11 penalty be removed?

A late-payment penalty applies if you can't pay in full. The IRS says to contact it by the due date on your notice, since the penalty may be removed depending on your situation. source 1

Sources

  1. IRS, Understanding your CP11 notice (updated August 11, 2026) (external site) checked Oct 19, 2026
  2. 26 U.S.C. section 6213 (deficiency procedures; math and clerical errors) (external site) checked Oct 19, 2026

Every rule on this page comes from the IRS page in the list, read on the date shown. Your notice itself is the final word on its own dates and amounts.