837P Electronic Claims Guide
NM1 Provider & Patient Identifiers
NM1 segments carry entity identity information such as billing provider, subscriber, patient and other provider roles.
Reviewed September 2026 · Educational reference — verify payer and program requirements.
What to look for
- Entity identifier code matters
- Name and identifier belong to the correct loop
- NPI and other IDs are context-dependent
- Do not treat every NM1 the same
Practical workflow
Start by identifying the transaction, claim or service line that the segment belongs to. Then compare the value or status to the implementation guide, payer companion guide and the source claim. Avoid correcting a raw segment in isolation without understanding the surrounding loop and trading-partner requirement.
Common troubleshooting sequence
- Confirm you are reading the correct interchange and transaction set.
- Match control numbers, claim identifiers and provider/patient context.
- Identify the segment, element or claim-level status that failed.
- Correct the source data or file-generation rule rather than only patching the output text.
- Regenerate, revalidate and resubmit according to the payer or clearinghouse process.
Official references
See the CMS Medicare FFS companion guides and Medicare Claims Processing Manual Chapter 24. Trading-partner requirements can differ.