270/271 eligibility transaction

The 270/271 is the HIPAA standard for checking a patient’s eligibility for a health plan, and Medicare’s EDI manual lists the current version as 005010X279A1¹. The 270 goes out with the question about a member’s coverage, and the 271 comes back with the payer’s answer: whether the member is covered, and the benefit details the payer returns. HHS also adopted operating rules for the transaction, written by CAQH CORE, which set business rules the standard itself does not define; compliance for eligibility began on January 1, 2013².

Medicare answers 270s through its own HIPAA Eligibility Transaction System, known as HETS. CMS says the system releases eligibility data to providers, suppliers and their authorized billing agents so they can prepare an accurate Medicare claim, work out what the beneficiary owes, or confirm eligibility for specific services³. HETS handles real-time transactions only and does not accept batch files, so each inquiry is sent and answered one at a time⁴.

Eligibility is a snapshot. A 271 says the coverage was active when the payer answered, not that the claim will pay: prior authorization, coordination of benefits and medical necessity are separate checks. The mistake is checking once at intake and never again. Coverage can end between visits, so run the 270 before each visit or trip, and keep the 271 with the encounter as a record of what the payer reported that day.