Does Your Medicare Patient Need To Sign An Advance Beneficiary Notice (ABN) CMS-R-131? Yes!  When applicable, your Medicare patients should always sign an Advance Beneficiary Notice (form CMS-R-131). An ABN is not used for commercial insurance companies. What Is An ABN? An ABN is a Medicare waiver of liability that providers are required to give a Medicare patient for services provided that may not be covered or considered medically necessary. An ABN is used when service(s) provided may not be reimbursed Continue Reading