What these notices are about We sent you a CP180 or CP181 notice because your tax return is missing a schedule or form. What you need to do Read the notice carefully to determine the required schedule or form needed to complete your return. Download the required schedule or form or call 800-829-3676. Fill out the Contact Information section of the notice, detach, and send it to us with your completed schedule or form so we receive it by the date indicated on the notice. You may want to Review the filing requirements and instructions for the missing schedule or form to determine whether your organization needs to file. Review your records to ensure all applicable schedules and forms were attached when filed. Frequently Asked Questions What happens if I don't respond by the due date? If you don't respond by the due date of the notice, your tax and/or credits may be adjusted which may result in a balance due. Who do I call for assistance? For assistance with your business return, call 800-829-0115 or, for assistance with Form 990-T, call 877-829-5500. Helpful information Publication 542, Corporations PDF Publication 559, Survivors, Executors, and Administrators PDF Publication 598, Tax on Unrelated Business Income of Exempt Organizations PDF Tips for next year Refer to the instructions for your tax return for required documentation. Attach all required forms and schedules to your tax return when filing. Consider filing your taxes electronically. Filing online can help you avoid mistakes and find credits and deductions that you may qualify for. In many cases you can file for free. Learn more about e-file. 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 usted autorizar a un representante para comunicarse con el IRS en su nombre. Vea si usted califica para recibir ayuda de las Clínicas para Contribuyentes de Bajos Ingresos. Si no puede encontrar lo que necesita en línea, llame al número del IRS en la parte superior de su aviso o carta.