EDI 270/271 (ASC X12N 270/271 005010X279A1): Eligibility & Benefit Loops, EQ/EB Segments, and CAQH CORE Rules

EDI 270/271 refers to the paired HIPAA-mandated electronic data interchange transaction sets—the ASC X12N 270 Eligibility, Coverage, or Benefit Inquiry and the ASC X12N 271 Eligibility, Coverage, or Benefit Information Response—governed by Technical Report Type 3 (TR3) Implementation Guide version 005010X279A1 under federal regulation 45 CFR § 162.1202. Together with sibling EDI in healthcare transactions such as EDI 837 (claims) and EDI 278 (prior authorization), the EDI 270/271 pair forms the technical backbone of real-time automated insurance verification and patient financial clearance across hospitals, ambulatory clinics, and clinical trial billing offices.

What Is EDI 270/271? The Request-and-Response Pair Explained

In revenue cycle management and Electronic Health Record (EHR) registration workflows, the 270 and 271 transactions operate as a synchronous or batch request-response cycle between a healthcare provider (or clearinghouse) and a health plan (Medicare, Medicaid, or commercial payer):

• EDI 270 (Eligibility, Coverage, or Benefit Inquiry): Transmitted by the provider’s EHR, Practice Management (PM) system, or patient intake platform to ask a payer whether a specific patient has active health plan coverage on a given service date and to request benefit details for specific Service Type Codes (such as general medical coverage `30`, hospital inpatient `48`, diagnostic radiology `62`, or pharmacy `88`).
• EDI 271 (Eligibility, Coverage, or Benefit Information Response): Returned by the payer (within 20 seconds for real-time inquiries under CAQH CORE Operating Rules), confirming whether the member’s policy is active or inactive and detailing plan name, network status, copayments, coinsurance percentages, total and remaining deductibles, out-of-pocket maximums, and whether prior authorization is required.

The 4-Level Hierarchical Loop Structure (2000A–2000D)

Both the ASC X12N 270 inquiry and the 271 response (`005010X279A1`) organize transaction data inside four nested Hierarchical Level (HL) loops enclosed within standard X12 interchange (`ISA`/`IEA`), functional group (`GS`/`GE`, functional identifier `HS` for 270 and `HB` for 271), and transaction set (`ST`/`SE`) envelopes:

Hierarchical Loop	HL Level Code	Entity Represented	Key Segments & Identifiers Carried
Loop 2000A (Subloop 2100A)	HL03 = 20	Information Source (Health Plan, PBM, or Government Payer)	NM1*PR (Payer Name and Payer Identifier, such as CMS/NAIC or clearinghouse payer ID), PER (Payer contact info), and AAA (source-level rejection errors).
Loop 2000B (Subloop 2100B)	HL03 = 21	Information Receiver (Hospital, Medical Group, or Rendering Provider)	NM1*1P or NM1*FA (Provider Name and 10-digit National Provider Identifier [NPI] with qualifier XX), REF (Tax ID / EIN), and PRV (Provider taxonomy code).
Loop 2000C (Subloops 2100C & 2110C)	HL03 = 22	Subscriber (Primary Insured Policyholder)	TRN (Trace Number), NM1*IL (Subscriber Name & Member ID with qualifier MI), DMG (Date of birth & sex), DTP (Service/Plan dates), and Loop 2110C containing EQ (in 270) or EB (in 271).
Loop 2000D (Subloops 2100D & 2110D)	HL03 = 23	Dependent (Spouse or Child Patient, omitted if Subscriber is the Patient)	NM1*03 (Dependent Name), DMG (Dependent DOB/sex), INS (Relationship code to subscriber), and Loop 2110D containing patient-specific EQ (in 270) or EB (in 271) segments.

Parsing the EDI 270 EQ Segment and the EDI 271 EB Segment

Within Loop 2110C (Subscriber) or Loop 2110D (Dependent), the 270 request sends one or more EQ (Eligibility or Benefit Inquiry) segments—most commonly EQ*30~ for a general health benefit plan inquiry or specific Service Type Codes (such as EQ*98~ for professional physician visit—office). The payer responds in the 271 with repeating EB (Eligibility or Benefit Information) segments that encode the patient’s exact coverage and cost-sharing rules across 12 data elements:

Element Position	X12 Element Name	Common Code Values & Clinical Billing Meaning
EB01	Eligibility or Benefit Information Code	1 = Active Coverage; 6 = Inactive Coverage; A = Coinsurance; B = Copayment; C = Deductible; G = Out-of-Pocket (Stop Loss); F = Limitations; I = Non-Covered; R = Other/Additional Payor (Coordination of Benefits / MSP alert).
EB02	Coverage Level Code	IND = Individual; FAM = Family; EMP = Employee Only; CHD = Children Only.
EB03	Service Type Code	30 = Health Benefit Plan Coverage; 1 = Medical Care; 33 = Chiropractic; 47 = Hospital; 48 = Hospital – Inpatient; 50 = Hospital – Outpatient; 88 = Pharmacy; 98 = Professional (Physician) Visit – Office; MH = Mental Health; UC = Urgent Care.
EB04	Insurance Type Code	HM = HMO; PO = PPO; EP = EPO; PR = Indemnity; MA = Medicare Part A; MB = Medicare Part B; MC = Medicaid; C1 = Commercial.
EB06	Time Period Qualifier	Critical for accumulators: 23 = Calendar Year (total annual deductible/OOP max); 29 = Remaining (remaining deductible/OOP balance as of inquiry timestamp); 27 = Visit.
EB07	Monetary Amount	Dollar value for copayment (when EB01 = B), deductible (EB01 = C), or out-of-pocket maximum (EB01 = G).
EB08	Percentage as Decimal	Patient coinsurance share expressed as a decimal (e.g., .2 = 20% patient coinsurance when EB01 = A).
EB09 & EB10	Quantity Qualifier & Quantity	Benefit visit or day limits (e.g., EB09 = VS [Visits] and EB10 = 20 for 20 physical therapy visits per year).
EB11	Authorization or Certification Indicator	Y = Prior Authorization Required; N = No Prior Authorization Required; U = Unknown.
EB12	In-Plan Network Indicator	Y = In-Network benefit tier; N = Out-of-Network benefit tier; W = Not Applicable (applies to both tiers).

Worked 271 EB Segment Example:
EB*C*IND*30**GOLD PPO*29*450*****Y~
Interpretation: Deductible (EB01 = C) at the Individual level (EB02 = IND) for general Health Benefit Plan Coverage (EB03 = 30) under the GOLD PPO plan has a Remaining balance (EB06 = 29) of $450.00 (EB07 = 450) for In-Network providers (EB12 = Y).

How Is EDI 270/271 Used in Clinical Research, CAQH CORE Compliance, and Error Handling?

Beyond routine clinic check-in, EDI 270/271 is governed by strict federal operating rules and supports clinical research billing compliance:

• CAQH CORE Operating Rules (Mandated under ACA Section 1104): Requires HIPAA-covered health plans and clearinghouses to support real-time 270/271 responses within ≤ 20 seconds (and batch responses by the next morning), return patient financial responsibility (copay, coinsurance, base deductible, and remaining deductible) across core Service Type Codes, and normalize patient name search logic.
• AAA Request Validation Error Segments: When a 270 inquiry fails subscriber lookup or formatting validation, the payer returns a 271 containing an AAA segment specifying whether the transaction can be resubmitted (`AAA01 = Y/N`), the Reject Reason Code in AAA03 (e.g., 72 = Invalid/Missing Subscriber/Insured ID; 73 = Invalid/Missing Subscriber/Insured Name; 58 = Invalid/Missing Date-of-Birth; 42 = Unable to Respond at Current Time), and a Follow-Up Action Code in AAA04 (e.g., C = Please Correct and Resubmit).
• Clinical Trial Qualifying Coverage & Medicare Advantage Screening: In oncology and interventional clinical trials, research billing teams inspect the 271 response (specifically EB04 = MA/MB or Loop 2120C secondary payer details when EB01 = R) to detect when a traditional Medicare Fee-for-Service participant has enrolled in a Medicare Advantage (`Part C`) plan or has a primary commercial working-aged policy, ensuring routine clinical trial costs are routed to the correct payer under the CMS Clinical Trial Policy (`NCD 310.1`).

Frequently Asked Questions

What is EDI 270/271?

EDI 270/271 is the HIPAA-mandated electronic transaction pair (ASC X12N Version 005010X279A1) used to verify patient health insurance eligibility and benefits. The EDI 270 is the electronic inquiry sent by a healthcare provider to a payer, and the EDI 271 is the electronic response returned by the payer detailing active coverage status, deductibles, copayments, coinsurance, and prior authorization requirements.

How is EDI 270/271 used in clinical research and healthcare?

In healthcare and clinical research, EHR and practice management systems transmit automated batch 270 inquiries 2 to 3 days before scheduled appointments and real-time 270 inquiries at check-in. The returned 271 response (`EB` segments) populates the patient’s active coverage status, calculates point-of-care copays and remaining deductibles, flags Coordination of Benefits or Medicare Advantage plans for clinical trial billing compliance, and alerts staff when a procedure requires prior authorization (`EB11 = Y`).

What is the difference between EB06 qualifier 23 and EB06 qualifier 29 in an EDI 271 response?

In an EDI 271 deductible or out-of-pocket segment (EB01 = C or G), EB06 = 23 (Calendar Year) reports the patient’s total annual deductible or out-of-pocket maximum for the plan year, whereas EB06 = 29 (Remaining) reports the exact dollar amount the patient still has left to satisfy as of the moment the 270 inquiry was processed.