Fast answer: Mismatch between submitted provider information and the provider information stored in the payer’s system.
How to use RARC N521
RARC N521 should be read with the CARC and group code on the same claim or service line. For BCBS denials, the remark often tells you whether the next move is a corrected claim, attachment response, COB update, authorization proof, or appeal packet.
Common paired CARCs
Recommended workflow
- Compare the 837 provider loops to payer enrollment, roster, taxonomy, location, and network/product records.
- Correct NPI/taxonomy/location fields if the claim is wrong.
- Open provider enrollment or credentialing escalation if the payer record is wrong.
- Attach roster effective dates, contract proof, and portal screenshots when disputing.
- Prevent recurrence by syncing PMS provider tables with the payer’s current provider file.
Evidence checklist
- Provider enrollment record
- NPI registry/taxonomy data
- Payer roster or contract proof
- Claim provider loops
- Portal screenshots
- Corrected claim notes
FAQ
What does RARC N521 mean?
Mismatch between submitted provider information and the provider information stored in the payer’s system.
Is N521 enough to appeal a BCBS denial?
No. Pair the RARC with the CARC, group code, EOB text, claim line, and plan rule. The RARC explains the missing detail or context; the CARC explains the adjustment reason.
What should I attach for N521?
Start with Provider enrollment record, NPI registry/taxonomy data, Payer roster or contract proof, Claim provider loops. Add only the records that answer the specific remark code and denial reason.