IRS & CT DRS Tax Letters Explained › CP24
IRS CP24 Notice Explained: Your Estimated Payments Didn't Match
By Andrew Nocera, Tax Preparer & Small-Business Finance Consultant, Enhance Finance LLC (serving all of Connecticut from Shelton). Updated November 2026.
A CP24 means the IRS changed your return because the estimated tax payments you claimed didn't match what it posted to your account, and you may have a credit. It's common for self-employed people and 1099 earners who pay quarterly.
IRSWe can help with this| What it is | Return corrected for an estimated-payment mismatch; you may have a credit. |
|---|---|
| Deadline | Agree: no response required. Disagree: contact the IRS "by the date indicated." |
| Official page | IRS: Understanding your CP24 notice |
What the CP24 is
The IRS says: "We corrected your return because we found a difference between the amount of estimated tax payments on your tax return and the amount we posted to your account. You may have a credit because of these changes. The notice may also cover other changes we made while processing your return." The IRS page covers CP24, CP24E, CP24G and CP24U.
Why you got it
- The estimated payments on your return don't match what posted to your account (a payment wasn't credited, was counted twice, or posted elsewhere).
- The amount carried over from the prior year differs from what you claimed. The IRS tells you to check "the payments we applied (if any) from the prior year."
- If you don't make estimated payments at all, the IRS says common causes are "an incorrect entry on the estimated tax line of the tax return, or an incorrect payment applied to your account."
Deadline
What to do, step by step
- Read "What we changed on your return" on the notice.
- List every estimated payment you made for that tax year, plus any prior-year overpayment you applied.
- Compare your list with the notice and with the payments in your IRS Online Account.
- If you agree, no response is needed. Correct the copy of the return you kept, but the IRS says don't send it in.
- If a payment is missing or misapplied, call the number on the notice by the date shown, with a copy of your return and proof such as cancelled checks.
- If a payment is listed that you didn't make, call too. The IRS says you'll need to return any refund you receive by mistake.
- Next year, check your online account before filing. The IRS says you can verify the estimated payments applied to the year there.
Common mistakes
- Counting a payment in the wrong year, such as a January payment that belongs to the prior tax year.
- Forgetting the prior-year overpayment you applied, or claiming more than was applied.
- Mixing up state and federal payments. A Connecticut estimated payment isn't a federal payment.
- Filing an amended return just to agree. No response is required if you agree.
- Spending a refund you got by mistake. The IRS says it has to be returned.
When to get help
Get help if you can't find where a payment went, the changes left you owing instead of getting a refund, or you want your quarterly payments set up so it doesn't happen again. See our Connecticut estimated tax payments guide for the 2026 dates.
General information, not advice for your situation. Not tax, legal, investment, or insurance advice. Agency rules and procedures change; always follow the instructions and dates on your own notice and check the official sources below.
Frequently asked questions
Do I need to respond to a CP24?
Only if you disagree. The IRS says if you agree with the changes, no response is required. If you disagree, contact the IRS at the number on the notice by the date indicated.
When will I get my refund after a CP24?
The IRS says you should receive your remaining refund within 4 to 6 weeks, as long as you do not owe other taxes or debts it is required to collect.
I do not pay estimated taxes. Why did I get a CP24?
The IRS says common causes are an incorrect entry on the estimated tax line of the return, or an incorrect payment applied to your account. Call the number in the notice.
What if a payment I made is missing from the notice?
Call the IRS at the number in the Where to find more information section of the notice. Have a copy of your return and documentation, such as cancelled checks, ready.
Sources (checked November 10, 2026)
- IRS, Understanding your CP24 notice (CP24, CP24E, CP24G, CP24U; no response if you agree; 4-6 weeks; disagree by the date indicated; FAQs): www.irs.gov
- IRS, Online Account for individuals: www.irs.gov
Paying quarterly and tired of mismatches? Get your federal and Connecticut estimates set up right with a Connecticut tax preparer.