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CO-101 Denial Code: Predetermination Estimate Only

CO-101 means the payer processed your submission as a predetermination, showing the payment it anticipates once services are completed or the actual claim is adjudicated. Nothing is paid yet; you still need to submit a claim after the service is performed.

Quick facts

Code
CO-101 (CARC 101)
Status
Active In use since January 1, 1995; last modified February 28, 1999.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The amount shown is not paid now. It is an anticipated payment from a predetermination, and no balance transfers to the patient or write-off is needed.
  • OA (Other Adjustment): Some payers use the other adjustment group because the predetermination carries no liability at all until a claim is filed.
Official description
Predetermination: anticipated payment upon completion of services or claim adjudication.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-101 means

CARC 101 stands for predetermination: anticipated payment upon completion of services or claim adjudication. You sent (or the payer treated your submission as) a request for a pre-treatment estimate. The payer responds with what it expects to pay once the work is done, and reports that estimate with CARC 101.

No money moves on a predetermination. The remittance is informational. Payment happens only after you submit a claim for services actually performed.

Predeterminations are most common in dental billing, where plans often review planned treatment such as crowns, bridges, or orthodontics. Some medical plans also offer pre-service estimates for high-cost procedures.

Common causes

  • You intentionally submitted a predetermination or pre-treatment estimate request.
  • A claim was sent with a predetermination indicator (or on a dental form with the pre-treatment box checked) when you meant to bill completed services.
  • Future dates of service on a claim caused the payer to treat it as a predetermination.
  • The payer’s system converted a claim for planned services into an estimate.

How to fix it

  1. Confirm the submission type. If you meant to request an estimate, CO-101 is the expected result. Save the estimate in the patient record.
  2. If you meant to bill completed work, resubmit as an original claim with actual dates of service and without the predetermination indicator. This is a new claim, not an appeal.
  3. After treatment, bill the claim with the performed services. Include the predetermination reference number if the payer requests it.
  4. Share the estimate with the patient, making clear it is not a promise of payment and that their share may change.
  5. Check authorization separately. If the plan requires prior authorization, a predetermination alone may not satisfy it.

How to prevent it

  • Set up separate workflows and claim types for predeterminations and actual claims so staff do not mix them.
  • Never send claims with future dates of service. Scrub for them before submission, for example with a Claims Validator.
  • Track outstanding predeterminations and link them to the eventual claim so nothing goes unbilled after treatment.
  • Review each payer’s rules on how long a predetermination remains valid and what changes require a new one.

Specialty notes

In dentistry, predeterminations often come back with the payer’s frequency limits and alternate benefit decisions already applied. If the estimate includes an alternate benefit, you may see CO-169 on the final claim. Explaining that to the patient before treatment prevents surprises.

  • CO-197 (Precertification/authorization/notification/pre-treatment absent.): Authorization absent. A predetermination is not always the same as the prior authorization a plan requires.
  • OA-18 (Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)): Duplicate claim, which can occur if a predetermination and a claim for the same service are confused.
  • OA-133 (The disposition of this service line is pending further review. (Use only with Group Code OA).): Service line pending further review, a different kind of non-final status.
  • CO-254 (Claim received by the dental plan, but benefits not available under this plan.): Dental plan received a claim without dental benefits, relevant where predeterminations are most common.

CO-101 FAQ

Does CO-101 mean the service is approved?

It means the payer estimated what it expects to pay. A predetermination does not guarantee payment, because eligibility, benefits, and the actual claim details can change.

Do I need to submit another claim after a CO-101?

Yes. After the service is completed, submit the actual claim with the real dates of service. Reference the predetermination if the payer asks for it.

Is a predetermination the same as prior authorization?

Not necessarily. Prior authorization is often a condition of payment, while a predetermination is typically an advisory estimate. Check whether the plan requires a separate authorization.