CP11

A CP11 says the IRS corrected what it believes were mistakes on your return — usually math or a mismatched figure — and the correction leaves a balance due. The change has already been made; the notice explains it and bills the difference.

“We changed your return, here's exactly what and why, and here's the new amount owed. Pay by the date on the notice, or arrange payments. If you disagree, contact us by the date indicated — most changes get reversed on request, no explanation required, though sending support speeds it up.”

The disagree deadline is the quietly important one: the IRS's own page says contacting them by the printed date preserves formal reversal rights and the right to appeal to the U.S. Tax Court. Later contact is still considered, but as a courtesy rather than a right.

• The notice, especially its 'What we changed on your return' section
• Your copy of the return, to see where the figures diverge
• The document behind the disputed number — a W-2, 1099, or schedule
• Payment records if the balance reflects a missed payment

• Determining whether the IRS's correction is actually right — these automated changes are frequently reversible
• Requesting the reversal inside the window so appeal rights survive
• Resolving the balance (payment, plan, or penalty relief) when the change stands
• Faxing the supporting document in during the call, which the IRS itself says is the fastest route