What Is an IRS CP11 Notice?

IRS Notices Explained
Written by Enrolled Agent
Reviewed by Enrolled Agent

The CP11 means the IRS found a math error on your tax return that resulted in a balance due. Here’s why you received it, what it means, and the steps you should take to prevent penalties and interest.

Quick Answer

An IRS CP11 notice tells you the IRS corrected a math error on your return and determined you owe additional tax. The letter includes your new balance and instructions for payment. If you disagree, you have the right to respond with documentation.

Important: CP11 balances accrue interest and penalties if unpaid. If you disagree, respond immediately; if you agree, pay or set up a resolution.

Why You Received a CP11

You made a math error on your return (calculation of credits, deductions, or taxable income).
The IRS automatically corrected the error and determined it results in a balance due.
The change was processed without your input, and now your account reflects the adjustment.

CP11 is different from CP12, which also corrects math errors but results in a refund or reduced balance.

What the CP11 Means

The IRS believes your return contained an error. They adjusted it, recalculated your liability, and determined you owe. The notice provides the corrected figures, your total balance, and payment instructions.

If you agree, payment is expected promptly. If you disagree, you must respond with evidence before the deadline to prevent enforced collection.

What to Do Next

Here’s how to respond based on your situation:

If you agree: Pay the balance in full, or request a payment plan to avoid further penalties.
If you disagree: Contact the IRS by the deadline on the notice and provide documentation to support your position.
If you’re unsure: Pull your IRS transcripts and compare them against your filed return and the CP11 changes.

Need the full roadmap? Start with our
IRS Notice Help Center and
Complete Guide to Back Taxes to understand how CP11 fits into the collection process.

If You Ignore the CP11

The balance will not disappear. The IRS will continue adding penalties and interest. If left unresolved, your account will proceed through the standard collection pipeline—CP501, CP503, CP504, and potentially levy notices like LT11.

Early response avoids escalation and gives you more resolution options.

How Polaris Can Help

Polaris Tax & Accounting helps taxpayers nationwide respond to CP11 notices. Our Enrolled Agents reconcile the IRS’s math changes against your return and transcripts, correct errors, and if necessary, secure a payment plan or penalty relief.

We handle the IRS communication on your behalf so you’re not left navigating deadlines alone.

Your Next Step: If you received a CP11, get clarity and resolution now.
Schedule a consultation.

Related Resources

FAQs

What’s the difference between CP11 and CP12?

CP11 means a math error caused you to owe more. CP12 means a math error resulted in a refund adjustment.

Can I appeal a CP11?

Yes. You can respond directly to the notice with documentation. If unresolved, you may have further appeal rights depending on the circumstances.

How quickly should I respond?

Immediately. The notice includes a deadline, typically 60 days. Acting fast avoids enforced collections.