ANSI X12 837 vs 835: Claims and Remittance Advice
The X12 837 is a healthcare claim submission; the X12 835 is the electronic remittance advice (ERA) that explains the adjudication. They are two halves of one round trip.
Updated 2026-09-30 · 6 min read
What the 837 is
The 837 is the ANSI X12 transaction used to submit a healthcare claim to a payer. It reports who the patient is, who is insured, what was done, and what is being charged.
There are three variants: 837P for professional claims, 837I for institutional claims, and 837D for dental. They share the envelope and the patient/subscriber loops and differ in the service-level detail.
What the 835 is
The 835 is the Electronic Remittance Advice (ERA). It returns the payer’s decision: which claims and service lines were paid, denied, or adjusted, and why.
The 835 is where claim adjustment reason codes (CARC) and remittance advice remark codes (RARC) appear. Those codes explain a denial or a reduced payment in machine-readable form.
How they pair
A provider sends an 837; the payer adjudicates; the payer returns an 835. The 835 references the original claim so the two can be reconciled.
Balancing is the check that the 835 adds up: submitted charge equals paid amount plus adjustments plus patient responsibility, line by line. A file that fails to balance is usually rejected before it reaches a downstream system.
| 837 Claim | 835 Remittance Advice | |
|---|---|---|
| Direction | Provider to payer | Payer to provider |
| Purpose | Submit a claim | Explain adjudication and payment |
| Key loops | 2000 patient, 2300 claim, 2400 service | 2000 payee, 2100 claim, 2110 service |
| Codes | CPT/HCPCS, ICD-10 | CARC, RARC |
Where machine parsing helps
Both transactions are hierarchical: an envelope contains functional groups, which contain transactions, which contain loops and segments. Fields are positional and delimiter-driven, so a single wrong delimiter shifts every field after it.
Parsing to typed JSON at the edge lets an integration catch structural and balancing errors before a claim is filed or a remittance is posted, rather than in a clearinghouse rejection report days later.
Try it on real data
Frequently Asked Questions
The 835 is the electronic equivalent of the paper Explanation of Benefits (EOB). It is the machine-readable remittance advice a payer returns for a claim.
CARC (Claim Adjustment Reason Codes) explain why a claim or line was adjusted; RARC (Remittance Advice Remark Codes) add detail or context. Both appear on the 835.
837P for professional (physician) claims, 837I for institutional (hospital) claims, and 837D for dental claims. The payer and the service type decide which is required.