CO-236: Procedure/modifier combination not compatible
UPDATED JULY 2026 · U.S. PLANS · NOT LEGAL OR MEDICAL ADVICE
The billed combination violates the payer's coding edits (often NCCI edits). Paperwork, not coverage.
CO-236 at a glance
- Code group: CO — Contractual Obligation — in-network providers generally cannot bill you for CO adjustments.
- Who usually fixes it: The provider’s billing office.
- Worth appealing? Rarely — usually fixed by resubmission.
What to do about a CO-236 denial
- Ask the billing office to correct and resubmit.
- No patient action needed in most cases — but confirm you're not being billed for it.
Denied? Don’t drop it
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