Check Medicare eligibility and determine Part A/B coverage using CMS eligibility resources

Steps

1. For providers submitting HIPAA-covered transactions, use the X12 270/271 transaction via the Medicare contractor (MAC) clearinghouse to query Medicare Part A and Part B eligibility, specifying service type codes '30' (health benefit plan coverage) or line-specific codes
2. Alternatively, use the Medicare Beneficiary Identifier (MBI) rather than the legacy HICN (Health Insurance Claim Number) in all eligibility inquiries; CMS retired HICN-based lookups for most transactions—the MBI is the required identifier
3. Parse the 271 response EB segments for Medicare-specific benefit codes: Part A hospital coverage, Part B medical coverage, Medicare Secondary Payer (MSP) indicators, and any HMO or managed care enrollment that would affect fee-for-service billing
4. Check for Medicare Secondary Payer (MSP) situations using the MSP auxiliary segment in the 271 or via CMS's HIPAA Eligibility Transaction System (HETS); an active MSP record means Medicare is not the primary payer and a COB workflow must be triggered
5. Log the eligibility response with the MBI, response date, and Part A/B effective dates; re-verify eligibility on each date of service since beneficiary enrollment status can change