What is an 837?
The 837 is the standard electronic claim. 837P carries professional claims (the CMS-1500), 837I institutional claims (the UB-04), and 837D dental claims.
ST*837*0001*005010X222A1~Start of an 837P professional claim transaction.BHT*0019*00*0123*20260315*1023*CH~Header: an original submission (00) of chargeable claims (CH).NM1*85*2*EXAMPLE FAMILY MEDICINE*****XX*1234567893~The billing provider and its NPI.NM1*IL*1*SAMPLE*ALEX****MI*XEH481207733~The subscriber and their member ID.CLM*CLM00418*320***11:B:1*Y*A*Y*Y~Claim CLM00418 for $320.00, place of service 11 (office), frequency 1 (an original claim).HI*ABK:M5416~The principal diagnosis, ICD-10 M54.16.SV1*HC:99214*210*UN*1***1~Service line: CPT 99214, $210.00, one unit, pointing to diagnosis 1.DTP*472*D8*20260314~Date of service: March 14, 2026.Every electronic claim in the United States travels as an X12 837. HIPAA made it the standard, so the same format works for every payer, though each payer adds its own rules on top.
The three flavors
- 837P, professional: physicians, therapists, suppliers and other non-facility billing. The electronic CMS-1500.
- 837I, institutional: hospitals, skilled nursing, home health and other facilities. The electronic UB-04.
- 837D, dental.
What a payer needs to find in it
The patient and subscriber, matched to the payer’s records. The billing, rendering and referring providers, each with a valid NPI. Diagnoses that support the procedures. Codes, modifiers, units and dates that pass the payer’s edits. Authorization numbers when the service required one. And for a corrected claim, the right frequency code with the payer’s original claim number.
What happens after it’s sent
The 837 is answered three times: a 999 for the file, a 277CA for each claim, and finally an 835 with the payment or denial. A claim isn’t safe until it has all three.
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