CO-198: Prior authorization exceeded

What causes CO-198?

• The approved unit or visit count was used up and treatment continued
• Services were rendered after the authorization date range ended
• The authorization covered a lower level of service than the one performed
• A second course of treatment was billed against the first authorization
• Nobody was tracking the remaining balance on the authorization while the patient was still in treatment

How do you fix a CO-198 denial?

1. Pull the authorization and count exactly what was approved against exactly what was billed — units, visits and date range, separately
2. Bill the portion that falls inside the authorization and handle the excess separately, rather than appealing the whole claim
3. For the excess, request an extension or retro-authorization with the clinical notes that justify why treatment continued
4. Where the payer allows it, ask for the extension BEFORE the last approved visit rather than after — several will not backdate at all

Can CO-198 be prevented?

This is a tracking failure, not a knowledge failure. Somebody has to hold the remaining balance on every open authorization and flag it before the last visit, which is exactly the job a prior authorization seat does.

A denial like this one is the recurring cost that medical billing outsourcing is built to take off your desk — a dedicated seat working the queue instead of it waiting for whoever has a free hour.

Codes worked the same way

CO-198 is taken back to the authorization. So are these, which is why a queue sorted by recovery route moves faster than one sorted by code number — the same person, in the same system, with the same evidence to hand, clears all of them in one pass.

• CO-197 — Prior authorization absent
• CO-288 — Referral absent
• CO-15 — Authorization number missing
• CO-39 — Authorization already refused
• CO-272 — Coverage guidelines not met
• N54 — Claim does not match the authorization

Specialties that name this among their costliest

These are specialties whose own worst denials include one of this kind. The line under each is the denial they name, quoted from their page so you can see what the link is based on.

• Ambulatory Surgery Centers
  Prior authorization obtained for the surgeon but not the facility
• Behavioral Health
  Authorization units exhausted mid-course without renewal
• Urology
  Prior authorization missing for advanced imaging
• Radiology
  Advanced imaging denied for missing prior authorization
• Ophthalmology
  An injection given after the drug authorization lapsed, or under an authorization written for a different agent than the one actually drawn up that day.
• Neurology
  Long-term video EEG authorized as an ambulatory home recording but performed as an admission to the epilepsy monitoring unit, so the facility days sit outside the authorization

What leaving it costs

Working a denied claim costs $57.23 per denied claim in administrative time (source) — before any of it is recovered, and whether or not it ever is.

Payers ultimately pay roughly 90% of claims even while using an initial denial to slow payment (source), so the reason one sits is rarely that nobody knows how to work it. Put your own denial count in.

Questions

Code descriptions are the standard X12 claim adjustment reason and remittance advice remark code text. Payer policies differ, and the payer’s own coverage policy governs any individual claim. This page is working guidance, not legal or clinical advice.