By Brandon Seigel, Chief Problem Solver · August 29, 2026 · 8 min read
The common codes
- CO-16 — Claim lacks information. Fix demographics and required fields at intake.
- CO-29 — Timely filing expired. Submit daily and track each payer's filing limit.
- CO-50 — Not medically necessary. Strengthen documentation of function and goals.
- CO-97 — Service bundled into another. Review NCCI edits and modifier use.
- CO-197 — Precertification or authorization absent. Tighten authorization tracking.
- CO-119 — Benefit maximum reached. Verify visit limits before treatment.
- PR-204 — Service not covered under the patient's plan. Verify benefits and inform the patient in writing.
Group codes matter
CO means contractual obligation — you usually can't bill the patient. PR means patient responsibility. Posting these correctly is the difference between accurate patient statements and angry patients.
Work denials while they're fresh
Each payer has an appeal window. A denial worked in days is often a simple correction. Our team works denials every business day inside your EMR, and patterns are reviewed by our Chief Billing Officer so the same denial doesn't keep coming back.
Quick answers
What does denial code CO-197 mean?
The payer requires precertification or authorization and it wasn't on file. It's usually prevented with front-end authorization tracking.
What is the difference between CO and PR denials?
CO is a contractual adjustment the practice absorbs. PR is patient responsibility that can be billed to the patient.
Sources and further reading
See exactly what's included in our medical billing services for therapy practices, how our percentage-of-collections pricing works, or browse common questions from practice owners.
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