Official X12 description
“Missing radiology report.”
Source: X12 Remittance Advice Remark Codes. X12 publishes and maintains the RARC set; always verify against the current release before building a claim workflow.
Paired CARC codes
RARC M31 almost never appears alone — it accompanies one of the CARCs below on the same 835 remittance line. Fix the CARC and the RARC typically clears; the RARC alone is informational.
| Paired CARC | What the CARC means |
|---|---|
| CARC 16 | Claim/service lacks information or has submission/billing error(s). |
| CARC 227 | Information requested from the Billing/Rendering Provider was not provided or was insufficient/incomplete. |
| CARC 251 | The attachment/other documentation that was received was incomplete or deficient. |
| CARC 252 | An attachment/other documentation is required to adjudicate this claim/service. |
What RARC M31 actually means
RARC M31 requires the radiology report attached. Submit and rebill.
Common root causes
- Radiology report not submitted.
Prevention checklist
- Radiology-attachment automation.
Resolution & appeal strategy — step by step
Because RARC M31 is supplemental to a CARC, the resolution path usually starts by fixing the underlying adjustment reason. A formal appeal of the RARC alone is rarely necessary.
- 1Attach report and resubmit.
Sample reconsideration language referencing RARC M31
Edit the bracketed fields before sending. Payer-specific reconsideration forms are often required — check the provider portal first.
How common is RARC M31?
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM handles RARC M31
QuickRCM reads RARC M31 alongside its paired CARC in the 835 LQ segment and routes the line to the correct worker queue with the right documentation already attached:
- Denial routing rules tuned to the CARC+RARC pair — the paired combination tells QuickRCM which documentation the payer will accept.
- Reconsideration template for this exact remark code pulls the supporting facts from the claim automatically.
- Pre-submission scrubs that catch the preventable drivers surfaced on this page before the 837 leaves the clearinghouse.
Frequently asked questions — RARC M31
What does RARC M31 mean?
RARC M31 is an X12 Remittance Advice Remark Code. The official X12 definition is: "Missing radiology report." It is supplemental to a Claim Adjustment Reason Code (CARC) on the same 835 line.
Which CARC is paired with RARC M31?
RARC M31 is most commonly paired with CARC 16, CARC 227, CARC 251, CARC 252. The CARC is the financial adjustment reason; the RARC is the informational remark. Fix the paired CARC first — the RARC usually clears with the corrected claim.
How do I resolve a RARC M31 remark on a remit?
Start from the root cause: Radiology report not submitted. First step: Attach report and resubmit. Because RARCs are supplemental, the resolution is almost always to address the paired CARC rather than appeal the RARC alone.
Where does RARC M31 appear on the 835 ERA?
RARC M31 is carried on the 835 Loop 2110 LQ segment alongside the CARC in the CAS segment of the same service line. The code and its X12 description also print on the paper EOB in the "Remark Code" or "Remark" column next to the corresponding denial or adjustment reason.
Is RARC M31 the same as ICD-10 code M31?
No. RARC M31 is a remittance-advice remark code published by X12 and carried on the 835. Any ICD-10 code with the same letters and digits is a diagnosis code on the 837 HI segment — a completely different code set maintained by the WHO/CMS. Use the transaction context (835 = RARC; 837 = ICD-10) to disambiguate.
Disclaimer
This page is operational reference for medical-billing professionals. It is not legal, clinical, or contractual advice. X12 code descriptors are maintained by the X12 External Code Lists; always verify against the current X12 release and the payer's own published policy before submitting or appealing a claim.