Acronym that translates as payer identification number. The current acronym is NPLANID (national plan identifier). Medicare patients that have a Medigap supplemental insurance plan must show the PAYERID number (often called the OCNA [Other Carrier Name and Address] key ) in Block 9d of the CMS-1500 insurance claim form. The Medicare fiscal intermediary transmits a Medigap claim electronically to the Medigap carrier after processing it for participating physicians. This is called a crossover claim. See NPLANID.