Which of the following identification numbers is used specifically within the Medicare program?

The Unique Provider Identification Number (UPIN) is specifically utilized within the Medicare program to identify healthcare providers. This number serves as a key element in the administration of Medicare services, helping to ensure that claims and services are accurately attributed to the correct provider. The UPIN, once an actively used identifier, was designed to streamline the process of provider verification and facilitate the billing process for Medicare patients.

In contrast, the Employer Identification Number (EIN) is primarily used for tax purposes to identify businesses and not specifically linked to Medicare. The Performing Provider Identification Number (PPIN) is associated with identifying individual practitioners, while the Group Provider Number pertains to group practices in a broader sense, but neither is specifically designated for use within the Medicare system as the UPIN is.