What Is a CAF Number and How Do You Get One?

A Centralized Authorization File (CAF) number is a unique identifier assigned by the Internal Revenue Service (IRS) to individuals authorized to interact with the agency on behalf of taxpayers. This nine-digit number helps the IRS manage and track authorizations for representatives. It ensures that only authorized parties can access confidential tax information or represent taxpayers in various matters.

What a CAF Number Is

CAF stands for Centralized Authorization File, an IRS computer database system. This system records information about individuals who have been granted authority to represent taxpayers or access their tax information. A CAF number is a unique nine-digit identification number the IRS assigns to a representative the first time they submit a power of attorney or a request for access to tax information.

The fundamental purpose of a CAF number is to centralize and track authorizations granted by taxpayers to their representatives. It allows IRS personnel to quickly verify whether a tax professional has the necessary authority to access a taxpayer’s data without repeatedly requesting authorization documents. While a CAF number identifies the file containing legal authorizations, it does not, by itself, indicate that the individual is authorized to practice before the IRS. It simply points to the centralized file where those authorizations are stored.

When a CAF Number is Used

A CAF number becomes relevant when a tax professional or other authorized third-party needs to interact with the IRS on behalf of a taxpayer. This typically includes individuals such as attorneys, Certified Public Accountants (CPAs), enrolled agents, or other designees who require formal authorization from their clients.

These professionals commonly use a CAF number when representing a taxpayer before the IRS, requesting confidential taxpayer information, or responding to IRS notices. For instance, when a representative needs to call the IRS on a client’s behalf or access their tax transcripts online, the CAF number serves as a shortcut for the IRS to confirm their approved status.

The primary IRS forms where a CAF number is entered are Form 2848, Power of Attorney and Declaration of Representative, and Form 8821, Tax Information Authorization. Form 2848 grants a representative the authority to perform specific tax-related functions and act on a taxpayer’s behalf, such as negotiating payment plans or signing documents. Conversely, Form 8821 allows a designated person to inspect and/or receive confidential tax information but does not grant the authority to act on the taxpayer’s behalf. Both forms require the representative’s CAF number for proper processing.

Obtaining and Using a CAF Number

To obtain a CAF number, a representative generally submits either Form 2848, Power of Attorney and Declaration of Representative, or Form 8821, Tax Information Authorization, to the IRS for the first time. On these forms, if a CAF number has not yet been assigned, the representative should enter “NONE” in the designated CAF number field. Upon processing this initial authorization, the IRS will assign a unique nine-digit CAF number to the representative and typically send a letter informing them of the newly assigned number.

These forms can be submitted to the IRS via mail or fax, with specific addresses and fax numbers depending on the representative’s geographic location. Alternatively, the IRS also offers an online Tax Pro Account site where tax professionals can request and receive their CAF numbers electronically after verifying their identity using ID.me. The processing time for an initial CAF number assignment can vary, often taking between two and six weeks.

Once a CAF number has been assigned, the representative should use this number on all future Forms 2848 and 8821, as well as in all subsequent correspondence and communications with the IRS. If a representative has an existing CAF number but cannot recall it, they can retrieve it by contacting the IRS Practitioner Priority Service (PPS) at 866-860-4259. A PPS assistor will help retrieve the number after identity authentication.