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CO-198 Denial Code: Authorization Exceeded

CO-198 means precertification, authorization, notification, or pre-treatment approval was exceeded. An approval was on file, but the claim billed more units, visits, or days than approved, or fell outside the approved dates. The excess is typically the provider's responsibility.

Quick facts

Code
CO-198 (CARC 198)
Status
Active In use since October 31, 2006; last modified May 1, 2018.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider absorbs the amount beyond the authorization under the network contract. It isn't billable to the patient.
  • PR (Patient Responsibility): Occasionally used when the plan makes the member responsible for services beyond what was approved, such as some out-of-network arrangements. Verify the plan terms first.
Official description
Precertification/notification/authorization/pre-treatment exceeded.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-198 means

CARC 198 reads “Precertification/notification/authorization/pre-treatment exceeded.” Unlike CO-197, the authorization isn’t missing. The claim just goes past what was approved. The most common forms are:

  • Units or visits exceeded: 12 therapy visits approved, 14 billed.
  • Dates exceeded: services delivered after the authorization’s end date.
  • Days exceeded: an inpatient or residential stay longer than approved.
  • Scope exceeded: a higher level of service or additional codes beyond what the approval covered.

Example: a physical therapy practice receives approval for eight visits over 30 days. The patient attends a ninth visit on day 28 without an extension. The payer pays eight visits and denies the ninth with CO-198.

Common causes

  • No tracking of used units against the approval, so staff don’t know when it runs out.
  • Extension requested too late or not at all.
  • Authorization end date passed while treatment continued.
  • Units billed per time increment (for example 15-minute units) that exceed the authorized count.
  • Approval for different codes than those billed, especially when the treatment plan changed.
  • Authorization linked to one provider or location while another billed part of the care.

How to fix it

  1. Pull the authorization and compare its units, codes, dates, and provider with the claim.
  2. If the claim was wrong (units, dates, or codes miscoded), submit a corrected claim with resubmission code 7 in box 22.
  3. If the payer’s authorization record was wrong, ask it to update and reprocess.
  4. Request an extension or retro update if the payer allows it, with clinical notes supporting the added services.
  5. Appeal when you requested the extension on time, or the additional services were medically necessary and the payer’s process allows review.
  6. Write off the exceeded portion if no remedy applies.

How to prevent it

  • Track remaining units and end dates for every authorization in your scheduling system.
  • Set alerts when a patient has a few visits or days left, and request extensions before they run out.
  • Match authorization codes to the codes you actually bill, and update approvals when the treatment plan changes.
  • Block scheduling past the authorization end date without an extension.
  • Monitor partial payments where units billed exceed units paid. ERA Analyzer can surface these unit shortfalls. See also authorization and referral denials and MUE and units denials.

Specialty notes

PT/OT/SLP practices and behavioral health providers see CO-198 most often, because ongoing care is authorized in blocks of visits. Inpatient and residential behavioral health programs see it when concurrent review approves fewer days than the stay lasted.

Remark codes that may appear with CO-198

  • N54 (Claim information is inconsistent with pre-certified/authorized services.): The claim information is inconsistent with the services that were authorized.
  • N45 (Payment based on authorized amount.): Payment was based on the authorized amount rather than the amount billed.
  • N362 (The number of Days or Units of Service exceeds our acceptable maximum.): The days or units billed exceed the payer's acceptable maximum.
  • CO-197 (Precertification/authorization/notification/pre-treatment absent.): No authorization was on file at all.
  • PR-119 (Benefit maximum for this time period or occurrence has been reached.): A benefit maximum for the period was reached, a plan limit rather than an authorization limit.
  • CO-151 (Payment adjusted because the payer deems the information submitted does not support this many/frequency of services.): The number or frequency of services isn't supported by the information submitted.
  • CO-15Deactivated (The authorization number is missing, invalid, or does not apply to the billed services or provider.): Deactivated. It once covered an authorization number that was missing, invalid, or not applicable to the provider. Today the same problem may be flagged with a remark code such as M62.

CO-198 FAQ

Can I extend an authorization after the fact?

Some payers allow extensions or updates shortly after the service, especially for ongoing therapy. Others require extensions before the approved units run out. Check the payer's rules and act quickly.

Does CO-198 deny the whole claim?

Often only the portion beyond the approval. Look at the paid units versus billed units on the ERA to see what was allowed.

What if the service was in the approved range but dated wrong?

If the date of service in box 24A was wrong, submit a corrected claim. If the authorization's dates were wrong in the payer's system, ask the payer to correct and reprocess.

How do I appeal CO-198?

Provide the authorization letter, records showing the medical need for additional services, and any extension request you submitted. Appeals are strongest when an extension was requested before the approval ran out.