What Is an Audit Number and Where Do You Find It?

An audit number is a unique identifier assigned by the Internal Revenue Service (IRS) to a specific tax return examination or inquiry. This numerical code acts as a distinct reference for the case, allowing for precise identification within the tax administration system. It signifies that a particular tax period or aspect of a tax return is under review and serves as a central point of reference for all related communications and documentation.

The Function of an Audit Number

The primary function of an audit number is to establish an organized system for managing tax examinations. The IRS uses these unique identifiers to track specific cases, ensuring all correspondence and internal processes are linked to the correct taxpayer and tax period. This systematic approach streamlines the agency’s operations from initial contact to audit resolution.

An audit number helps the IRS maintain a clear record of all interactions related to a particular audit. It allows the agency to organize incoming documents, refer to previous communications, and allocate resources effectively for each case. This administrative tool supports the consistent application of tax laws.

For the taxpayer, the audit number provides a straightforward way to identify and manage their specific tax inquiry. It ensures that communications with the IRS are directed to the correct department and associated with the precise examination. This helps maintain clarity and prevents misdirection of information or actions throughout the audit process.

Locating Your Audit Number

The IRS initiates tax audits by sending official correspondence through the mail. This initial contact, such as a CP notice or an audit letter, will contain the audit number. Various types of notices, including those proposing changes to a tax return or requesting additional information, will feature this identifier.

The audit number, often referred to as a notice number, is usually located in a prominent position on the document. Taxpayers can typically find this number in the top right corner of the IRS letter or notice. While the exact placement may vary, it is generally presented clearly for easy identification.

Any official communication from the IRS regarding an audit, such as a letter informing a taxpayer of an audit and providing contact details for the assigned agent, will include this reference. Locating this number should be a priority when reviewing IRS correspondence.

How to Use an Audit Number

Once a taxpayer locates their audit number, its proper use is essential for effective communication with the IRS. When contacting the IRS by phone regarding an audit, providing the audit number immediately allows the representative to quickly access the correct case file. This saves time and focuses the discussion on the specific examination.

When responding to an IRS audit by mail, include the audit number on all written correspondence, documents, and cover letters. This ensures submitted information is accurately associated with the ongoing audit, preventing delays or misplacement. Taxpayers should also include their name and Social Security Number (SSN) on each page of documentation sent to the IRS.

Some IRS online portals or tools might require this number to access case information or upload documents. Using the audit number consistently across all interactions—by phone, mail, or online—helps maintain an organized record of the taxpayer’s engagement with the IRS. This ensures communications are correctly routed and processed, contributing to a smoother resolution of the tax examination.