Verifying Medicare Eligibility

eligibility verification: a request goes out and a response comes back, typically as the X12 270/271 inquiry-and-response pair described in how electronic eligibility checks work. What differs for Medicare is the identifier used, how coverage is structured into program parts, the federal source that answers the request, and an added question about which payer is responsible first.

• A program-specific identifier — the Medicare Beneficiary Identifier (MBI) — rather than a commercial member ID.
• Coverage split into parts (Part A, Part B, and separate plans for Part C and Part D) instead of a single plan record.
• A federal eligibility source for original Medicare (the HIPAA Eligibility Transaction System, HETS), which clearinghouses and vendors route to.
• A Medicare Secondary Payer (MSP) screening step that asks whether another payer must be billed before Medicare.

The Medicare Beneficiary Identifier (MBI) is an eleven-character, randomly assigned identifier printed on the beneficiary's Medicare card. It replaced the older Health Insurance Claim Number (HICN), which was based on a Social Security number; the SSN-based identifier has been retired, and Medicare's eligibility system now expects the MBI on the inquiry. Capturing the MBI exactly as it appears on the card is the foundation of a usable Medicare eligibility check.

MBI (Medicare Beneficiary Identifier)

The current randomly generated identifier used to look up a beneficiary and submit Medicare claims; it carries no personal meaning and is unique to the person.

HICN (legacy claim number)

The former Social Security–based identifier, now retired; inquiries submitted with a legacy number generally do not return usable benefit information.

For original Medicare, the eligibility response reports Part A and Part B entitlement and their effective dates separately. The two do not always move together: a beneficiary can be entitled to Part A while Part B is inactive, or coverage for a part may begin on a specific date. Reading these fields is part of confirming active coverage and effective dates and interpreting them accurately is covered in reading an eligibility response.

Medicare is not always the first payer. Under Medicare Secondary Payer (MSP) rules, another payer is primary in certain situations — for example, an employer group health plan for a working beneficiary or a covered spouse, a group health plan in some disability cases, workers' compensation, or no-fault and liability coverage. Which situation applies varies by the individual's circumstances, so it cannot be assumed from age or enrollment alone. Establishing the order of payers is coordination of benefits applied to Medicare.

1. 01

   Ask standardized MSP questions

   At or near registration, staff work through a consistent set of questions about other coverage — employment, spousal coverage, accident or injury circumstances, and similar factors — often using a model Medicare Secondary Payer questionnaire so the same ground is covered each time.
2. 02

   Determine whether Medicare is primary or secondary

   The answers indicate whether Medicare pays first or whether another payer is primary. This is a screening determination, not a clinical or legal one, and it feeds the front-desk eligibility workflow.
3. 03

   Record the payer order and any other coverage

   Accurate capture of the primary payer and policy details supports a clean claim; incomplete MSP information is a common source of eligibility-related denials.

This article stops at the eligibility step. When MSP screening shows another payer is primary, that payer is billed first and Medicare is billed afterward — the mechanics of secondary billing and verifying secondary and tertiary coverage are handled separately, and deeper Medicare claim rules belong to their own cluster.