Dental denial codes: what each one means, and what the front office does next
The adjustment and remark codes dental offices see most on EOBs and ERAs, who owes the money for each, and a page on each with the dental causes and fixes.
By Dr. Salem Sayegh, general dentist, Glendora, California ·
The short answer: a code on a dental EOB is a group (CO means the office absorbs it, PR means the patient owes it) plus a reason number, sometimes with a remark code that adds detail. Most search results explain these codes for medical billing. The pages below explain the ones dental offices see most, with the dental procedures that trigger them and what to do.
| Code | What it means | Bill the patient? |
|---|---|---|
| CO-45 | Charge exceeds the fee schedule or maximum allowable amount | No, not the CO-45 amount |
| CO-97 | The benefit for this service is included in the payment for another service already adjudicated | Usually not when in network; check your contract |
| CO-16 | The claim or service lacks information, or has a submission or billing error | No. Fix the claim and resubmit |
| CO-252 | An attachment or other documentation is required to process the claim | No. Send the documentation |
| CO-29 | The time limit for filing has expired | No, when in network |
| CO-22 | This care may be covered by another payer under coordination of benefits | Not yet. Rebill the right plan first |
| CO-18 | Exact duplicate claim or service | No |
| CO-197 | Precertification, authorization or pre-treatment estimate absent | Usually not when in network |
| CO-119 | The benefit maximum for this time period or occurrence has been reached | Usually yes, if they were told and your contract allows it |
| CO-50 | Not covered because the payer does not consider it necessary | Usually not when in network, unless they agreed in writing in advance and your contract allows it |
| PR-1 | Deductible amount | Yes |
| PR-96 | Non-covered charge | Yes |
| N130 | Consult the plan’s benefit documents for restrictions on this service | Depends on the reason code and your contract |
New to reading these? Dental claim adjustment codes explains the group codes, how reason and remark codes fit together, and why paper EOB codes do not always match the ERA. For one line you cannot work out, ask Sai Biller, our free chatbot.
Sources
- X12 claim adjustment reason codes and remittance advice remark codes. Meanings here are paraphrased; see X12 for the official wording.
Common questions
What are the most common denial codes on dental claims?
CO-45 (above the fee schedule) appears on almost every in-network line but is a write-off, not a denial. The most common true denials on dental claims are CO-97 (bundled into another procedure), CO-16 and CO-252 (missing information or attachments), CO-119 with N130 (maximums and frequency limits), CO-22 (coordination of benefits) and CO-29 (filed too late).
What does CO mean versus PR on a dental EOB?
CO means contractual obligation: the office absorbs the amount under its contract and cannot bill the patient. PR means patient responsibility: the patient owes it. The number after the letters is the reason.
Are dental denial codes the same as medical denial codes?
The electronic remittance (835) uses the same national X12 code list for both. What triggers each code, and how to fix it, is often different in dentistry, because dental claims carry tooth numbers, frequency limits and alternate-benefit clauses instead of modifiers and medical-necessity edits.
