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Your IRS CP21A Notice, Explained
Also called: Notice CP21A
Last reviewed 2026-07-12
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What this notice usually means
IRS Notice CP21A tells you the IRS made changes to your tax return. You owe money because of those changes. This can follow a change you requested or a change the IRS made on its own. The notice explains what changed and lists the amount and the date to pay.
See every source line for this notice
“If you agree with the changes we made, pay the amount you owe by the date printed on your notice”
“Yes, interest will accrue if you don't pay the full amount you owe by the date on the payment coupon.”
“Yes, you'll be charged a late payment penalty.”
What to do now
- 1
Pay by the date printed on your notice if you agree
Paying online can help make sure your payment is received on time and helps avoid interest.
- 2
Look into payment options if you cannot pay in full
If you cannot pay it all at once, you have options. You can ask about a payment plan, a delay, or an offer in compromise.
- 3
Correct your own copy of your return
Update the copy of your tax return that you kept for your records to match the changes.
- 4
Call the IRS if you disagree
Contact the IRS at the number on your notice if you disagree with the changes made.
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Your notice shows the exact date to pay. Interest starts to add up on any part you have not paid by the date on your payment coupon.
“We sent you this notice because we made the changes to your tax return. You owe because of the changes.”
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Sources
- Internal Revenue Service (irs.gov)Retrieved 2026-07-12
Last reviewed 2026-07-12
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