The CAF Number and the Centralized Authorization File, Explained

Every time you sign a Form 2848 or Form 8821 and the IRS records it, the authorization lands in a database called the Centralized Authorization File, or CAF. The person you authorized gets a CAF number. Most taxpayers never think about either. You should, at least once, because the CAF decides who the IRS will talk to about your account.

What the CAF is

The Form 2848 instructions describe the CAF system as a computer file system containing information regarding the authority of individuals appointed under powers of attorney. It gives IRS personnel quicker access to authorization information without requesting the original document from the taxpayer or representative.

In practice, when your representative calls the IRS, the employee checks the CAF to confirm the representative is authorized for your account, for that tax matter, for that period. If the authorization is not on the CAF, or does not cover the year being discussed, the conversation stops.

What a CAF number is

A CAF number is a unique nine-digit identification number the IRS assigns to representatives and designees. The Form 2848 instructions are specific about what it is not: it is not the representative's Social Security number, EIN, PTIN or enrollment card number. And the CAF number is not an indication of authority to practice. It identifies a person in the database. It does not license them.

How a representative gets one. The IRS assigns a CAF number when a person files a first power of attorney or tax information authorization. If the representative does not have a number, the form instructions say to enter "None" and the IRS will issue one directly to the representative. According to the IRS's Tax Pro Account page, the IRS mails Letter 1727C when it assigns a CAF number after a first Form 2848 or 8821 is filed. Practitioners can also get an individual CAF number on Tax Pro Account; a business CAF number requires a Form 2848 or 8821.

Use the same number every time. The instructions tell representatives to use the assigned CAF number on all future powers of attorney, and to use the identical full name on all submissions.

Lost numbers. If a representative cannot find the CAF number, the IRS says to check records for Letter 1727C and, if it cannot be found, to contact the IRS.

What the CAF does not hold

Not every authorization goes on the CAF. Line 4 of both forms is for specific-use authorizations that the IRS does not record centrally. Examples in the instructions include private letter ruling requests, EIN applications, Form 843 claims, ITIN applications and FOIA requests for Form 2848, and disclosures to lenders or for background checks for Form 8821. Those go to the IRS office handling the specific matter, and the representative brings a copy to meetings.

Non-IRS powers of attorney, such as a durable power of attorney drafted by your estate planning lawyer, also cannot be recorded on the CAF unless a completed Form 2848 is attached.

Why the CAF matters to you

It determines who can get your information. Anyone recorded on the CAF for a matter can inspect and receive your confidential tax information for that matter. That is the point, when you want it. It is a problem when you have forgotten about an old authorization.

New forms can silently revoke old ones. When the IRS records a new Form 2848, it generally revokes earlier powers of attorney on the CAF for the same matter, unless you check the retention box on line 6 and attach a copy of the one you want to keep. Form 8821 works the same way on line 5. Filing a Form 2848 does not revoke a Form 8821.

Future years are limited. The IRS will not record on the CAF future periods more than 3 years after December 31 of the year it receives the form. If your representative needs to cover later years, a new form will be needed.

Notice copies are limited. No more than two representatives on Form 2848, or designees on Form 8821, can receive copies of IRS notices for the same matter.

When the form is not on the CAF yet

Processing takes time, and the IRS says it processes forms in the order received, whether they arrive online, by fax or by mail. Until an authorization is recorded, the IRS employee on the phone may not be able to see it. The IRS's online submission page gives two options when a representative needs to discuss a case immediately: fax the form, with a wet ink signature, to the IRS employee handling the matter, or contact the Practitioner Priority Service. The IRS also provides a page to check Form 2848 and 8821 processing status.

Students, law graduates and automatic purges

One group of representatives has a built-in expiration date. Students and law graduates working in Low Income Taxpayer Clinics or Student Tax Clinic Programs can represent taxpayers with permission from the Taxpayer Advocate Service, with the lead attorney or CPA listed on the form as well. Under the Form 2848 instructions, for each separate representation, the CAF automatically purges the student or law graduate as a representative 130 days after the taxpayer's signature date. If your case runs longer, the clinic will handle the paperwork, but it is worth knowing why a student's authority can lapse. See Low Income Taxpayer Clinics.

How to find out who is on your CAF record

There is no single public lookup, but there are routes.

1. Ask the IRS on the phone. When you call about your account, you can ask whether any authorizations are on file for the years in question.
2. Check your online account. The IRS says your individual online account lets you approve and electronically sign powers of attorney and tax information authorizations from your tax professional, and view authorization requests from lenders. See your IRS online account.
3. Make a FOIA request. The IRS FOIA guidelines address requests for CAF records specifically: if the request is for the Centralized Authorization File, you must attach a valid photo identification that includes your signature as proof of identity, and failure to include one may result in denial. See requesting your IRS file under FOIA.

Representatives have their own route. The Form 2848 instructions say representatives can receive a list of their powers of attorney recorded on the CAF by following the FOIA request instructions on IRS.gov. Representatives who link their CAF number in Tax Pro Account can also view all their active authorizations recorded on the CAF and withdraw in real time.

A quick example

Say you hired an enrolled agent in 2023 under a Form 2848 for your 2020 through 2022 income tax. In 2026 you hire an attorney for the same years and file a new Form 2848 without checking the retention box. When the IRS records the new form, it generally revokes the enrolled agent's authority for those same matters. If you want both on file, perhaps because they are working together, check the line 6 box on the new form and attach a copy of the enrolled agent's form. The CAF follows the paperwork exactly, so the paperwork has to say what you mean.

Keeping your CAF record clean

• When you hire a new representative for the same matter, decide whether the old one should stay. If yes, check the retention box and attach a copy. If no, let the new form revoke the old one, or revoke it yourself.
• When a relationship ends, revoke. See revoking a power of attorney or tax information authorization.
• When you change address, file Form 8822. Your address on Form 2848 or 8821 does not update the IRS's records.
• Keep a copy of every authorization you sign, with the date you sent it and how.

The CAF is plumbing. You do not need to understand every pipe. You just need to know where the shutoff valve is.