CP12

A CP12 says the IRS corrected a mistake on your return and the correction changed your refund — sometimes creating one you didn't expect, sometimes shrinking the one you did. If you agree with it, no response is needed at all.

“We fixed one or more errors and your refund is now different. If you agree, do nothing — the check arrives in four to six weeks unless it's offset against other debts. If you disagree, contact us by the date on the notice, and we'll reverse most changes on request.”

Agreeing requires nothing. Disagreeing has the same quiet stakes as the CP11: contact by the printed date preserves formal reversal rights and Tax Court appeal rights; contact after it is considered but not guaranteed.

• The notice's 'What we changed' section
• Your copy of the return
• The source document for whichever line changed
• Nothing at all, if the correction looks right

• Verifying the correction — reduced refunds are sometimes the IRS mis-reading a credit that was claimed correctly
• Requesting reversal inside the window with the right documentation
• Tracking down the refund when the promised weeks pass without it
• Amending properly when the correction reveals a bigger issue in the return