List of IRS CP Notices

What Are IRS CP-Series Notices?

Common IRS CP-Series Notices and Their Meanings

Balance Due & Payment Notices

Tax Return & Adjustment Notices

Earned Income Tax Credit (EITC) & Identity Verification Notices

Underreported Income & Audit Notices

Refund Delay & Adjustment Notices

Business & Payroll Tax Notices

How to Respond to CP-Series Notices

Frequently Asked Questions

##### What should I do if I disagree with the information in a CP-Series Notice?

##### What happens if I ignore a CP-Series Notice?

##### Can I negotiate the proposed changes in a CP2000 notice?

##### How can I set up an installment agreement to pay my tax debt mentioned in a CP-Series Notice?

##### What should I do if I cannot pay the full amount mentioned in a CP503 or CP504 notice?

Getting mail from the IRS can cause anxiety for many taxpayers, especially when those envelopes have codes such as CP12, CP2000, or CP503 on them. These CP notices, collectively referred to as the CP-Series Notices, are letters that the IRS uses to pass important information about your tax return, payments, or other related matters. To avoid issues with the IRS, you have to learn what these common IRS notices mean, how you can interpret them, and most importantly, how to respond effectively.

CP-Series Notices are a group of standardized letters and notices issued by the IRS to address various issues related to a taxpayer’s individual or business tax return. These notices cover a wide range of topics, including adjustments to your tax return, overdue tax payments, and other discrepancies that may need your attention. Each notice in the CP-Series is designated by a specific code, such as CP2000, CP503, CP12, etc., to help both the IRS and the recipient identify the type of issue being addressed.

Here, we've classified these notices according to the financial/tax issue they're trying to address. They include the following:

Responding to CP-Series Notices is essential to address any discrepancies or issues and avoid potential consequences. Here are the general steps you should take:

To set up an installment agreement, follow the instructions provided in the notice or visit the IRS website to explore online payment options and request an installment agreement.

If you cannot pay the full amount, you may consider setting up an installment agreement or making an offer in compromise (OIC) to settle the debt for less than the full amount. Contact the IRS to discuss these options.

Request a free consultation with our experts today and take the first step towards achieving your goals.

This content was written and reviewed by the licensed tax attorneys at Victory Tax Lawyers, LLP. Our attorneys specialize in IRS tax relief and are licensed members of the California State Bar with a nationwide practice.

Last Reviewed: 2026  ·  Meet Our Attorneys →

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