IRS CP23 Notice: Estimated Payment Mismatch — Balance Due
A CP23 notice means the estimated tax payments the IRS has on record don't match what you claimed on your return, so your refund changed or you now owe — usually because a payment was misdated, misapplied, or claimed twice.
Deadline calculator
The CP23 clock runs from the date printed on the notice — not the day you opened it.
Estimate only, based on the standard 21-day CP23 window. Your notice controls — always use the specific date printed on it.
What a CP23 actually means
Self-employed filers see these most. Common causes: a January estimated payment claimed in the wrong year, a payment applied to a spouse's account after a name/SSN mixup, or simple typos in the payments claimed.
If the IRS record is wrong, proof of payment fixes it. If your return overstated payments, the balance is real but the penalties are often abatable.
What to do, step by step
- 1Compare the IRS's payment list against your bank records and IRS online account.
- 2If a payment is missing from their list, respond with proof (confirmation numbers, bank statements).
- 3If you actually overclaimed, pay the difference or set up a plan, and ask about penalty abatement.
- 4Fix the source going forward — schedule estimated payments through your IRS online account so they're always applied correctly.
Common questions
The IRS says I made fewer estimated payments than I did — what do I do?+
Respond with payment proof: IRS confirmation numbers, EFTPS records, or bank statements. Payments applied to the wrong year or spouse's account are the usual culprits and get corrected on documentation.
Received a CP23? Get it handled.
Talk to a tax specialist about your notice — free, no pressure, no judgment.