How do I resolve a CO-50 denial?

If a payable diagnosis is indicated in the patient's encounter / service notes or record, correct the diagnosis, and resubmit the claim. Do not resubmit an entire claim when a partial payment has been made. Correct and resubmit denied lines only. See full Medicare contractor resolution steps at tryarceum.com.

Can I appeal a CO-50 denial?

Yes. Most CO-50 denials can be appealed within 60-180 days depending on payer. Medical necessity determinations are appealable with supporting clinical documentation that demonstrates the service was appropriate and necessary for the patient's condition. Use our free tool to generate an appeal letter.

CARC Code

50

🔴 Hard Denial

Service Not Medically Necessary

The insurance company determined that the service provided was not medically necessary according to their coverage guidelines. This means they believe the service was not essential for diagnosing or treating the patient's condition.

medical necessity

Resolution: 48%Hard difficulty30-90 days avg

How to resolve this denial

Which payer denied this claim?

▶✓ Pre-action checklist — verify before contacting the payer

Does the procedure have a Local Coverage Determination (LCD) or National Coverage Determination (NCD)?
Were all required diagnosis codes included to support medical necessity?
Was the correct place of service code used?
Check if the payer requires specific documentation submitted with the claim.

Still denied?

Formal Appeal

If the payer upheld the denial after reconsideration, you can submit a formal appeal.

Generate appeal letter →

▶More about CO-50 — stats, related codes, appeal template

48%

Recovery Rate

30-90 days

Avg. Resolution

Hard

Difficulty

Common

Frequency

Payer-Specific Notes

How major payers handle CARC 50 by specialty.

Medicare

Follow LCD/NCD criteria strictly; include all required ICD-10 codes that establish medical necessity

UnitedHealthcare

Prior auth and medical necessity are separate; approved auth does not guarantee MN approval

Aetna

Clinical Policy Bulletins (CPBs) define medical necessity criteria; reference specific CPB in appeal

Common 835 Combinations

CARC 50 most often appears with these Group Code + RARC combinations on 835 remittances.

COCO-50The payer has denied the service as not medically necessary under the contractAppealable COCO-50+N115The service was denied as medically unnecessary based on a specific LocalAppealable COCO-50+N163The payer has denied the service as medically unnecessary based on aAppealable COCO-50+N130The payer has denied the service as not medically necessary under the patient'sAppealable COCO-50+M86The payer has denied the service as not medically necessary because payment wasAppealable COCO-50+N518The payer denied separate reimbursement for oxygen accessories because theyAppealable COCO-50+N130+N115The payer denied the claim based on medical necessity determination under theAppealable COCO-50+N567The payer has denied the service as not medically necessary because it wasAppealable

Look up any combination →

Appeal Letter Template

Generic appeal template for CARC 50 denials.

We are appealing the medical necessity denial for claim [CLAIM_NUMBER] (CPT: [CODE], DOS: [DOS]). The enclosed clinical documentation from Dr. [PHYSICIAN] demonstrates that [SERVICE] is medically necessary for this patient due to [CLINICAL_RATIONALE]. We request peer-to-peer review if this appeal is not resolved in our favor.

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