low urgency
IRS Notice CP12 / CP21B: Refund Adjustment
What it means
The IRS corrected an error and changed your refund — often no action needed.
What to do
Compare the changes to your return; dispute only if wrong.
Verify it's real. The IRS contacts you by mail first — never by phone, email, or text demanding payment. The notice includes a number in the top-right corner and instructions on irs.gov. When in doubt, log into your IRS online account rather than calling a number on the letter.
FAQ
What is IRS notice CP12 / CP21B?
The IRS corrected an error and changed your refund — often no action needed.
How long do I have to respond to CP12 / CP21B?
No formal deadline, but resolving it quickly keeps the account clean.
Should I get professional help for CP12 / CP21B?
Usually not required — but if the amounts are wrong or you also owe other years, a professional review is cheap insurance.