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In the IRS’s own words · not reviewed by VALID

CP101 notice explained, in the IRS’s own words

We made changes to your return because we believe there's a miscalculation. You owe money on your taxes as a result of these changes.

Read the full CP101 page on irs.gov ↗

Quoted from www.irs.gov/individuals/understanding-your-cp101-notice, read October 15, 2026 · fingerprint 002d3f20a798 · 1 line left out here (see irs.gov)

What this notice is about

We made changes to your return because we believe there's a miscalculation. You owe money on your taxes as a result of these changes.

What you need to do

  • Read your notice carefully. It will explain why you owe.
  • Compare the figures on the notice with your tax return.
  • Pay the amount you owe by the date on the notice's payment coupon.
  • Make payment arrangements if you can't pay the full amount you owe.
  • Contact us within 10 days of the date of your notice if you disagree with the changes we made.
  • If you agree with our changes, correct the copy of your tax return that you kept for your records.

Frequently asked questions

How can I find out what caused my tax return to change?

Please contact us at the number listed on your notice for specific information about your tax return.

What should I do if I disagree with the changes you made?

If you disagree, contact us at the toll-free number listed on the top right corner of your notice. If you contact us in writing within 10 days of the date of this notice, we’ll reverse the change we made to your account. However, if you can’t provide us additional information that justifies the reversal and we believe the reversal is in error, we’ll forward your case for audit. After we forward your case, the audit staff will contact you within five to six weeks to fully explain the audit process. If you don’t contact us within 10 days, you’ll lose your right to appeal our decision before payment of tax. If you don’t contact us within 10 days, we won’t reverse the change and you must pay the additional tax. You can then file a claim for refund PDF. You must submit the claim within three years from the date you filed the tax return, or within two years from the date of your last payment for this tax.

What happens if I can't pay the full amount I owe?

You can set up a payment plan to pay over time.

Am I charged interest on the money I owe?

Not if you pay the full amount you owe by the date on the payment coupon. However, interest accrues on the unpaid balance after that date until you pay the balance in full.

Will I receive a penalty if I can't pay the full amount?

Yes, you will receive a late payment penalty. You can contact us at the number given on your notice if you can't pay the full amount shown in your specific notice because of circumstances beyond your control. Contact us by the due date of your payment and, depending on your situation, we may be able to remove the penalty.

Tips for next year

Consider filing your taxes electronically.

What to do next

  • Write down the date on the letter today.
  • Look the number up on irs.gov yourself. Don’t trust a link or phone number from anyone else.
  • If it says you owe money or proposes changes to your return, take it to a licensed CPA, EA or tax attorney before that date.

Not advice. Not a filing. Verify with a licensed professional. Rules change by year and facts.

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