EDI 837: The Health Care Claim, Explained in Depth

The EDI 837 is the Health Care Claim. It is how a medical provider - a clinic, hospital, physician, or dentist - bills an insurance payer for services delivered to a patient. In the United States, the 837 is one of the core transactions mandated by HIPAA for electronic healthcare administration, which means almost all electronic medical claims flow through it.

The 837 and 835 cycle

The 837 does not travel alone. After a provider submits an 837 claim, the payer responds with an 835 (Health Care Claim Payment / Remittance Advice), which explains how each claim was adjudicated: paid in full, paid in part, denied, or applied to patient responsibility such as a deductible or copay. The provider's billing system then matches the 835 back to the original 837 to reconcile what was billed against what was paid. This 837-out, 835-back loop is the heartbeat of medical revenue-cycle management.

Three variants of the 837

The 837 comes in three flavors, distinguished by the type of provider and care:

• 837P - Professional. Claims from physicians, clinics, and individual practitioners. The most common variant.
• 837I - Institutional. Claims from hospitals and facilities, with additional detail about admissions, revenue codes, and facility charges.
• 837D - Dental. Dental claims, with tooth and oral-cavity detail.

All three share the same overall structure but differ in some segments and code sets. A given file is one of these variants, identified by the implementation guide version in the message.

The key segments of an 837

BHT - Beginning of Hierarchical Transaction

Opens the claim transaction with a structure code, a reference identifier, a date and time, and a purpose. It signals that what follows is organized into hierarchical loops, much like the 856 ASN.

NM1 - Individual or Organizational Name

This is the segment that surprises people coming from retail EDI. Healthcare does not use N1; it uses NM1. The entity identifier code in the first element says who the party is: 41 submitter, 40 receiver, 85 billing provider, 87 pay-to provider, 82 rendering provider, IL insured or subscriber, QC patient, PR payer. A second element distinguishes a person (1) from an organization (2). For a person, the name is split into last name, first name, and middle name; for an organization, the name sits in a single field. NM1 segments also carry standardized identifiers like the NPI (National Provider Identifier) and member ID.

CLM - Claim Information

The claim itself: a claim submitter identifier and the total claim charge amount, plus facility and signature indicators. CLM*PATIENT-A*450.00 indicates a claim identified as PATIENT-A with total charges of $450.00.

SV1 - Professional Service

Each billed service line, with a procedure code and charge. SV1*HC:99213*125.00*UN*1 means CPT/HCPCS procedure 99213, charged at $125.00, one unit. The 837I institutional variant uses SV2 with revenue codes instead.

DTP - Date or Time Period

Carries clinically important dates such as the date of service, admission, or discharge.

HI - Health Care Diagnosis Codes

The diagnosis codes (ICD-10) that justify the services billed. Payers use these to determine medical necessity.

A simplified worked example

ST*837*0001~
BHT*0019*00*REF12345*20240220*0900*CH~
NM1*41*2*RIVERSIDE MEDICAL GROUP*****46*9988776~
NM1*40*2*BLUE CROSS*****46*BCBS001~
NM1*85*2*RIVERSIDE MEDICAL GROUP*****XX*1234567890~
NM1*IL*1*DOE*JOHN****MI*ZGP9876543~
CLM*PATIENT-A*450.00***11:B:1*Y*A*Y*Y~
SV1*HC:99213*125.00*UN*1~
SV1*HC:85025*325.00*UN*1~
SE*9*0001~

In plain English: Riverside Medical Group is submitting a claim to Blue Cross for patient John Doe. The claim totals $450.00 and includes two services: an office visit (CPT 99213) at $125.00 and a blood count (CPT 85025) at $325.00.

A serious note on privacy

An 837 contains protected health information (PHI): patient names, member IDs, diagnosis codes, and service details. Under HIPAA, this data is legally sensitive and its handling is tightly regulated. That makes confidentiality essential when inspecting claims.

This is exactly why EdiPeek parses everything locally in your browser and never uploads your file. The claim data never travels to a server, which makes it safe to inspect real 837 files without sending PHI anywhere. Even so, treat any unredacted claim with care and avoid pasting real PHI into tools that do upload data.

Common pitfalls when reading an 837

• Looking for N1. Healthcare uses NM1, not N1. If you cannot find the parties, look for NM1 loops.
• Person vs organization names. The second NM1 element (1 or 2) tells you whether to read the name as last/first or as a single organization name.
• Confusing billing and rendering providers. The billing provider (85) and the rendering provider (82) can differ, especially in group practices.

Frequently asked questions