Build the 837P transaction set using the 005010X222A2 implementation guide: construct the ISA/GS envelope, then the Billing Provider loop (NM1/N3/N4/REF NPI), Subscriber loop (NM1 for payer and subscriber), and Claim loop (CLM, DTP service dates, SV1 service line with procedure code and charge)
Validate required fields before transmission: NPI (National Provider Identifier), payer ID, subscriber ID, ICD-10 diagnosis codes in HI segments, and CPT/HCPCS procedure codes in SV1 segments; reject internally if any required field is missing or malformed
Transmit the 837P to the clearinghouse via SFTP or API; the clearinghouse performs a 999 functional acknowledgment check—parse the 999 to confirm the interchange was accepted or rejected at the structural level
Await the 277CA (claim acknowledgment) from the clearinghouse or payer to confirm each individual claim was accepted into the adjudication queue; a 277CA rejection indicates a claim-level error requiring correction and resubmission
Track claim submission status through 276/277 transactions or the clearinghouse portal; reconcile accepted claims against your accounts receivable worklist and flag any claims not acknowledged within 48 hours for investigation
Known gotchas
A 999 acceptance only confirms the file was structurally valid—it does not mean claims will be paid; 277CA rejections at the claim level are separate and must be monitored independently
Rendering provider NPI must appear in the SV1 or loop 2310B when different from the billing provider; omitting it for group practices causes claim rejections at payers that require it
ICD-10-CM codes must be coded to the highest level of specificity supported by the available clinical documentation; undercoding or using unspecified codes where a more specific code is available can trigger medical necessity edits or reduced reimbursement
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp