How do I resolve a CO-173 denial?

Verify whether a physician prescription exists in your records: Check if the ordering/prescribing physician documentation was obtained prior to service delivery and meets payer requirements for format and content Obtain or complete the physician prescription if missing: If no prescription exists, contact the treating or supervising physician to issue a retroactive order if clinically appropriate and permitted by payer policy Submit a formal appeal with the physician prescription and clinical documentation: Include the original or corrected prescription, proof of the physician-patient relationship, clinical notes supporting medical necessity, and a letter explaining why the prescription requirement was met

835 Denial Combination

CO-173

Contractual Obligation · Service-Line Level Adjustment

Authorization/Referral Issue

What This Combination Means

The payer denied this claim because the service or equipment was furnished without a physician prescription when one was required. Under your contractual agreement, you must write off the denied amount and cannot bill the patient. This typically occurs when non-physician providers order services that require physician oversight or when DME suppliers deliver equipment without proper prescribing documentation.

Financial Responsibility

provider writeoff

The provider must absorb the full denied amount per contract terms. The patient has no financial liability for this adjustment.

75%

Appeal Success

30-60 days (appeal required)

Avg. Resolution

Hard

Difficulty

Yes

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-173 combination — not generic advice.

Appealable:CO authorization denials are appealable when the provider can demonstrate that a valid physician prescription existed but was not properly documented or received by the payer.

1
Verify whether a physician prescription exists in your records
Check if the ordering/prescribing physician documentation was obtained prior to service delivery and meets payer requirements for format and content
2
Obtain or complete the physician prescription if missing
If no prescription exists, contact the treating or supervising physician to issue a retroactive order if clinically appropriate and permitted by payer policy
3
Submit a formal appeal with the physician prescription and clinical documentation
Include the original or corrected prescription, proof of the physician-patient relationship, clinical notes supporting medical necessity, and a letter explaining why the prescription requirement was met

Specialty Context

How CO-173 typically presents across different practice types.

Dental

Medical

Common for therapies (PT, OT, speech), diagnostic tests, home health services, and procedures performed by non-physician practitioners that require physician orders or supervision under Medicare and commercial plan rules

Behavioral Health

May occur when counselors or therapists provide services that require physician referral or prescription under the plan's terms, or when psychiatric medications or testing are ordered without proper physician oversight

Individual Code References

View the standalone definition for each code in this combination.

CARC 173

Medicare Contractor Guidance for CARC 173

Noridian

Service/equipment was not prescribed by a physician Incomplete/invalid prescription

How to Prevent CARC 173 Denials

✓
Ensure a valid order is on file in the medical record

Noridian Medicare Portal

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Synthesized from official definitions — not from training data

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