IRS Notice CP23: What It Means & What to Do
CP23 means the IRS found a difference between the estimated tax payments on your return and what it posted, and you owe. Learn how to check your payments and respond.
Written and maintained by Joseph Lancaster, Settlement Officer since January 2013
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Quick answer
What is an IRS CP23 notice and what should I do?
CP23 means the estimated tax payments on your return did not match what the IRS posted, and you owe. Check every payment against your records; if one is missing or misapplied, call with proof. If you agree, pay by the date on the notice.
Who this applies to: People whose reported estimated tax payments differ from IRS records.
What can change this answer
- Fixing a misapplied payment adjusts penalties and interest automatically
- A late payment penalty usually applies if you cannot pay in full
- An incorrect estimated tax line is the most common cause
Recommended next step
Compare your payment records with the notice, then call or pay by the date shown.
Read the full guideCP23 means the IRS corrected your return because the estimated tax payments you reported did not match the payments it posted to your account, and you now owe. The notice may also cover other changes made while processing your return.
Immediate Steps to Take
- 1Compare every estimated payment on the notice with your own records
- 2Check whether a prior-year overpayment was applied to this year
- 3If a payment is missing or misapplied, call the number on the notice with proof such as cancelled checks
- 4If you agree, pay by the date shown or arrange to pay over time
What CP23 means
The IRS sends CP23 when it finds a difference between the estimated tax payments on your return and the amount it posted to your account, leaving you with a balance due. The notice may also include other changes made while processing your return.
If you do not make estimated payments at all, the IRS says the most common cause is an incorrect entry on the estimated tax line of the return. Call the number in the notice's "Where to find more information" section.
Check your payments before you pay
- Confirm the IRS listed every estimated payment you made for the year.
- Check any prior-year overpayment that was supposed to be applied.
- If a payment is missing or misapplied, call with a copy of your return and proof such as cancelled checks.
Your IRS account transcript shows the payments the IRS has on record for the year.
Penalties on a CP23 balance
If you cannot pay the full amount, the IRS says you will usually get a late payment penalty. If it adjusts your account, for example by fixing a misapplied payment, the penalty and interest adjust automatically. A separate estimated tax penalty can apply if you did not pay enough during the year. See our penalty abatement guide for relief options.
Frequently Asked Questions
I don't pay estimated taxes. Why did I get a CP23?
The IRS says the most common cause is an incorrect entry on the estimated tax line of the return. Call the number on the notice to sort it out.
What if the IRS missed one of my estimated payments?
Call the number on the notice with a copy of your return and proof of payment, such as cancelled checks. If the IRS fixes the payment, related penalties and interest adjust automatically.
What if I agree with the CP23?
Pay the amount by the date on the notice to avoid more penalties and interest, or arrange to pay over time if you cannot pay in full.
Authority Citations
This content is based on the following official IRS sources. All links open in a new tab.
Information current as of 2026. Tax laws change frequently. Verify with official IRS sources before taking action.
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