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RARC N450 · Remittance Advice Remark Code

RARC N450 Remark Code: Covered only when performed by the primary treating physician or the designee

Reviewed by QuickIntell RCM Editorial Team · Last reviewed

Updated

Not an ICD-10 code. RARC N450 is a remittance-advice remark code published by X12 and carried on the 835 LQ segment. Any ICD-10 code with the same letters and digits (e.g., ICD-10 M15 osteoarthritis, N130 other urinary tract disorders) is a separate, unrelated code set used in diagnoses on the 837. Confirm the context before acting on this page.

TL;DR

RARC N450 (X12 Covered only when performed by the primary treating physician or the designee). Commonly paired with CARC 170, CARC 185. RARC N450 denies services not performed by the primary treating physician or authorized designee.

Official X12 description

“Covered only when performed by the primary treating physician or the designee.”

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 N450 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 CARCWhat the CARC means
CARC 170Payment is denied when performed/billed by this type of provider.
CARC 185The rendering provider is not eligible to perform the service billed.
CARC 183The referring provider is not eligible to refer the service billed.

What RARC N450 actually means

RARC N450 denies services not performed by the primary treating physician or authorized designee. Rebill under the correct provider or document designee delegation.

Common root causes

  • Service performed by unauthorized secondary provider.

Prevention checklist

  • PTP/designee designation at authorization.

Resolution & appeal strategy — step by step

Because RARC N450 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.

  1. 1Rebill from authorized provider or submit designee documentation.
Sample reconsideration language referencing RARC N450
[Provider letterhead] Re: Reconsideration — Claim #{claim_number}, CARC 170 / RARC N450 Member: {member_name} · Member ID: {member_id} Date(s) of Service: {dos} The 835 remittance on {remittance_date} carried RARC N450: "Covered only when performed by the primary treating physician or the designee." We request reconsideration. The attached documentation rebuts the remark code: 1. [State the fact that rebuts the remark — authorization number, primary 835, modifier rationale, LCD citation, etc.] 2. [Reference the paired CARC and the corresponding fix] 3. [Attach the supporting document listed in step 1] Attached: {list supporting documents} Please process this line under the member's benefits. Contact the billing office at {provider_phone} for questions. Sincerely, {billing_manager_name}, {credentials}

Edit the bracketed fields before sending. Payer-specific reconsideration forms are often required — check the provider portal first.

How common is RARC N450?

Platform frequency
Pending ETL

Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).

How QuickRCM handles RARC N450

QuickRCM reads RARC N450 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.
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Frequently asked questions — RARC N450

What does RARC N450 mean?

RARC N450 is an X12 Remittance Advice Remark Code. The official X12 definition is: "Covered only when performed by the primary treating physician or the designee." It is supplemental to a Claim Adjustment Reason Code (CARC) on the same 835 line.

Which CARC is paired with RARC N450?

RARC N450 is most commonly paired with CARC 170, CARC 185, CARC 183. 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 N450 remark on a remit?

Start from the root cause: Service performed by unauthorized secondary provider. First step: Rebill from authorized provider or submit designee documentation. Because RARCs are supplemental, the resolution is almost always to address the paired CARC rather than appeal the RARC alone.

Where does RARC N450 appear on the 835 ERA?

RARC N450 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 N450 the same as ICD-10 code N450?

No. RARC N450 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.