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CP45 notice: what it means and what to do
Got an IRS CP45 notice? Here is what it means, your deadline, what to check before you answer, and how to reply. Check your own letter free: it stays on your phone.
Check my CP45 notice freeWhat the IRS says this notice is about
We couldn't apply your overpayment to your next year’s estimated taxes like you asked.
What you need to do
- Read your notice carefully - it explains why we couldn't apply your overpayment and may include next steps.
- Update your own copy of your tax return for your records.
- Adjust the amount of your current year's estimated tax payments so you don’t end up underpaying.
Your deadline
Answer by the date printed on your notice. If there is no date, answer as soon as you can, and call the number on the notice if you need more time.
What to check before you answer
Is this letter really from the IRS?
The IRS writes first by mail. A real letter shows a notice or letter number, your name and part of your tax ID number. The IRS does not ask for payment by gift card, crypto or wire transfer. If in doubt, sign in to your IRS online account, where many notices are listed.
You may want to
- Explore your payment options if you need help paying any remaining balance.
- Access your Online Account to view your account information.
Common questions
How do I calculate my estimated tax payments? (updated Nov. 24, 2025)
Use Form 1040-ES, Estimated Tax for Individuals PDF to calculate and adjust your estimated payments. You can also check Publication 505, Tax Withholding and Estimated Tax for more guidance.
What is an "overpayment," and how is it different from a "refund?" (updated Nov. 24, 2025)
An overpayment means you paid more tax than you owed during the year - either through paycheck withholding or estimated payments. You can choose to have this extra amount refunded or applied to your next year's taxes.
How can I find out what changed on my return? (updated Nov. 24, 2025)
Call us at the number shown on your notice. We can explain exactly what happened with your tax return.
Will the IRS send me another notice to confirm the overpayment has been applied? (updated Nov. 24, 2025)
No. This notice is your confirmation of how we applied your overpayment to your account.
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