What this notice is about We received your Form 2848, Power of Attorney and Declaration of Representative, Form 8821, Tax Information Authorization, or Form 706, U.S. Estate Tax Return, and we assigned you a Centralized Authorization File (CAF) number. What you need to do Keep this notice so you know what your CAF number is for all future third party authorization requests and telephone contacts with the IRS on behalf of the taxpayer. You may want to Keep your CAF number in a safe place for future reference. Notify the IRS if this was assigned without your knowledge. Frequently asked questions What is a CAF number? A CAF number is a unique nine-digit identification number that we assign to you the first time you file a third-party authorization with the IRS. We send a CP547 notice to you informing you of your assigned number. Use your assigned number on all future authorizations. If we assigned you more than one CAF number and you didn’t specifically request more than one, please fax a copy of each CP547 notice you received to the fax number in the notice using either a fax machine or an online fax service. Protect yourself when sending digital data by understanding the fax service’s privacy and security policies. What should I do if I don’t remember my CAF number? If you’re a tax professional and can’t remember your CAF number, you can call the Practitioner Priority Services (PPS) at 866-860-4259. Once authentication is verified for the client and representative, your CAF number can be provided over the phone. If the Customer Service Representative (CSR) is unable to authenticate you as the owner of the CAF number, a 1727C Letter will be issued to the CAF address of record for the representative. Herramientas de referencia Publicación 1 (SP), Derechos del Contribuyente Publicación 594 (sp), El Proceso de Cobro del IRS PDF Publicación 1660 (SP), Derechos para la Apelación de Cobros PDF Aviso 746, Información Sobre su Aviso, Multas e Intereses PDF Pago de impuestos Lista completa de formularios y publicaciones tributarios (en inglés) ¿Necesita ayuda? Puede autorizar a alguien para comunicarse con el IRS en su nombre. Vea si califica para recibir ayuda de una Clínicas para Contribuyentes de Bajos Ingresos. Si no puede encontrar lo que necesita en línea, llame al número del IRS que se indica en la parte superior de su carta o aviso. Si no recibió una carta o aviso, utilice la asistencia telefónica. Si no puede resolver la multa por su cuenta, comuníquese con el Servicio del Defensor del Contribuyente, una organización independiente dentro del IRS.