CO-198: Precertification exceeded (more visits/units than authorized)
UPDATED JULY 2026 · U.S. PLANS · NOT LEGAL OR MEDICAL ADVICE
Authorization existed but covered fewer visits, days, or units than were used. The overflow gets denied.
CO-198 at a glance
- Code group: CO — Contractual Obligation — in-network providers generally cannot bill you for CO adjustments.
- Who usually fixes it: You and the billing office together.
- Worth appealing? Yes — commonly appealed.
What to do about a CO-198 denial
- Ask the provider to request an authorization extension covering the additional units.
- If care is ongoing, get the extension request in before more visits accumulate.
- Appeal denied overflow units with clinical notes showing why the extra care was needed.
Best next read: Prior authorization denials — the full guide (with a free letter template) for this denial type.
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