IRS Notice CP23: Estimated Tax Payment Discrepancy

What does an IRS CP23 notice mean?

A CP23 tells you the IRS adjusted your return because the estimated tax payments you claimed differ from the payments the IRS has on record, and the difference resulted in a balance due. The notice compares your claimed payments to the IRS's records.

Why did you receive a CP23?

Common causes include claiming an estimated payment the IRS cannot locate, a payment credited to the wrong year or spouse's account, or a simple data-entry error on either side.

How to respond to a CP23 notice

Compare your payment records — canceled checks, bank statements, or IRS online account history — to the notice. If you can prove a payment the IRS missed, send documentation showing the date, amount, and tax year. If the IRS is right and you overstated payments, pay the difference or set up a plan.

What happens if you ignore it?

The balance becomes final and accrues penalties and interest, then proceeds through collection. If a payment really was misapplied, documenting it promptly is the fastest way to clear the balance.

Common resolutions

• Provide proof of payments
• Pay the difference

Related IRS notices

• CP21B — Adjusted Return — Balance Due
• CP30 — Estimated Tax Penalty
• CP24 — Estimated Tax Overpayment