IRS Notice CP23: Estimated payments didn't match — you owe
Quick answerThe estimated tax payments you claimed on your return don't match what the IRS has on file. The IRS corrected the return, and you now owe.
Letter / noticeCP23
MeaningEstimated payments didn't match — you owe
Action needed?Yes — see steps
Why you got this
- A payment was applied to the wrong year or wrong SSN
- A payment was claimed but never made or reversed
What happens next
If you can prove the missing payment, the balance can be corrected.
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What you should do
- Compare your payment records (bank, EFTPS, IRS online account) with code 660 entries
- Send proof of any missing payment
- Otherwise pay by the due date
Scam check: the IRS first contacts you by mail. Use only the phone numbers printed on your letter or on IRS.gov — never ones from a text, email or unofficial site.
Frequently asked questions
What does IRS Notice CP23 mean?
The estimated tax payments you claimed on your return don't match what the IRS has on file. The IRS corrected the return, and you now owe.
Why did I get IRS Notice CP23?
Common reasons: A payment was applied to the wrong year or wrong SSN; A payment was claimed but never made or reversed.
What should I do?
Compare your payment records (bank, EFTPS, IRS online account) with code 660 entries Send proof of any missing payment Otherwise pay by the due date
How long does it take?
If you can prove the missing payment, the balance can be corrected.
Sources
- IRS: Understanding your IRS notice or letter
- IRS: Get Transcript
- Taxpayer Advocate Service (independent help inside the IRS)
Written by the editorial team and checked against the official sources above. See our editorial policy.
By the TranscriptCodes Editorial Team · Last reviewed 2026-11-12.