Quick Explanation
Denial code CO-173 indicates that the billed service, procedure, or medical equipment was not officially ordered or prescribed by the patient's attending physician. Payers require a valid, documented prescription or order from the provider responsible for the patient's care to establish medical necessity prior to reimbursement. Without this documented authorization on the claim or in the medical record, the service is deemed non-covered.
Common Causes for CO-173
Denials with code CO-173 typically happen for the following specific reasons:
- Missing or incomplete ordering/referring physician information in Box 17 and 17b on the CMS-1500 claim form.
- The attending physician's order or prescription was not signed or dated prior to the service being performed.
- A discrepancy exists between the attending provider listed on the claim and the provider who actually signed the treatment order in the electronic health record.
- The billed procedure or diagnostic test does not align with the specific clinical order written by the prescribing provider.
How to Prevent CO-173 Denials
To avoid receiving this denial in the future, implement these specific checks:
- Implement automated claim scrubber rules to verify that Box 17 (Name) and 17b (NPI) are populated for all ordered services, such as lab tests, imaging, physical therapy, and DME.
- Establish a strict clinic workflow requiring a signed and dated physician order to be uploaded to the patient's chart before scheduling or rendering services.
- Perform regular pre-billing audits to cross-reference the clinical order with the final billing codes to ensure exact alignment of services.
- Educate clinical and billing staff on payer-specific guidelines regarding who qualifies as an attending or ordering practitioner for specialized services.
Appeal Letter Template for CO-173
If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.
[Your Practice Header]
[Date]
[Payer Name]
[Appeals Department Address]
RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: CO-173 - Service was not prescribed by attending physician
Dear Appeals Department,
I am writing to appeal the denial of the above-referenced claim, which was denied with code CO-173: "Service was not prescribed by attending physician".
We are appealing the denial for claim code CO-173, as the services rendered on the specified date of service were fully prescribed and medically directed by the patient's attending physician. Enclosed, please find the comprehensive medical record, which includes the signed and dated physician order dated prior to the service, establishing clear clinical intent and satisfying the billing requirements outlined in CMS Medicare Benefit Policy Manual, Chapter 15, Section 80. Because the enclosed documentation substantiates a valid, authorized order from the attending provider, we respectfully request that you reverse this denial and process the claim for immediate payment.
Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].
We respectfully request that you reprocess this claim for payment.
Sincerely,
[Your Name]
[Title]
[Practice Name]
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