A CAF number is a unique nine-digit identification number and is assigned the first time you file a third party authorization with IRS. A letter is sent to you informing you of your assigned CAF number. Use your assigned CAF number on all future authorizations.
CAF numbers are different from the third party's TIN (Taxpayer Identification Number), EIN (Employer Identification Number) or PTIN (Preparer Identification Number). CAF numbers may be assigned to an individual or a business entity.
If you are a tax professional and cannot remember your CAF number, you may call the Practitioner Priority Service, otherwise known as PPS. PPS may be reached at (866) 860-4259. To obtain or hear instructions on how to retrieve a lost or forgotten CAF number, you must first choose from the initial prompts. Choose either Individual accounts (IMF) or Business accounts (BMF). Once you provide your authenticating information, they can verbally give it to you over the phone. If PPS is unable to authenticate you as the owner of the CAF number then PPS will mail the number to the CAF address of record.