Dental claim denial codes

How the two code sets work

CARCs are maintained by the Claim Adjustment Status and Reason Code Maintenance Committee under ASC X12, which is chartered by ANSI. RARCs are maintained by CMS. Both lists are published at x12.org — they used to live at the WPC site, which now points readers to x12.org.

Both lists are updated three times a year, on or around March 1, July 1, and November 1. Each cycle adds codes, modifies wording, and deactivates codes — deactivated, not removed: a retired code keeps its row and gains a stop date.

The registry keeps two different dates, and confusing them is how live codes get published as dead ones. Last Modified means the description was revised; Stop means the code was deactivated on that date, and X12 usually adds a note naming the replacement. A code with only a Last Modified date is current, however old that date looks.

The group code decides who owes it

A group code always travels with a CARC, and it — not the reason number — assigns financial responsibility. X12 fixes the permitted group code for only a handful of codes; for the rest the payer chooses under its own contract, so a guide that tells you a given CARC “is CO” is asserting something the standard does not say.

CO — Contractual Obligation

CMS says this group code applies where a contract between payer and payee, or a regulatory requirement, produced the adjustment, and that generally the amount is a provider write-off rather than a patient bill. Both hedges matter: the trigger can be regulatory rather than contractual, and whether billing the patient breaches anything turns on the practice's own participation agreement.

PR — Patient Responsibility

CMS says this group code applies where the amount may be billed to the patient or insured, and names deductible and copay adjustments as the typical uses.

OA — Other Adjustment

The residual bucket. CMS says it applies where no other group code fits.

PI — Payor Initiated Reduction

X12 publishes the name and nothing else. CMS does not list PI among the group codes valid on a Medicare remittance, so it is a commercial-payer phenomenon and no CMS document describes how it behaves.

Which CARC and RARC combinations a payer may send in a CORE-defined business scenario is fixed by the CAQH CORE code-combination list, not by X12. HIPAA-covered entities have 90 days from each publication to comply, and the list itself publishes about three months after the underlying code-list update — roughly a six-month lag end to end. The list in force is v3.10.0, February 2026, with a mandated compliance date of 2026-05-01. It is a maximum set that payers may not add to, and a plan whose business requirements are not met by a scenario is not required to use that scenario's combinations at all.

Code index (39 codes)

The appealability verdicts on these pages are Dentovio's editorial classification. No standards body or payer publishes an appealability taxonomy: X12 defines what a code means, not what to do about it. Each verdict is built from the code's own mechanics and the payer and federal documents cited on the page, and it is a starting point for triage rather than a prediction of any outcome.

Official descriptions are published by X12 in the Claim Adjustment Reason Codes registry and the Remittance Advice Remark Codes registry. X12 holds the copyright in both lists; the meanings above are Dentovio's own wording for dental context, not X12's text.

The 42.8% service-exclusion and 18.1% benefit-limit shares cited on the CARC 96 and CARC 119 pages come from one plan-level filing — Covered California — Delta Dental 2024 individual-market plan-level claims-denied filing. They describe that filing, not national dental outcomes.

Can we bill the patient? Common questions

The most-asked front-office question is not what a code means but who ends up owing the money. Each answer below is the group-code question in disguise.

The remittance says CO — do we have to write it off?

Read the group code, then read your participation agreement, because the code reports the obligation rather than creating it. CMS states that group codes assign financial responsibility for the unpaid portion of the balance — CO (contractual obligation) to the provider, PR (patient responsibility) to the patient — and that Medicare beneficiaries may be billed only where group code PR is used with the adjustment. That sentence is Medicare fee-for-service scope, and Medicare covers almost no dentistry. X12's own framing is softer: group codes generally assign responsibility for the adjustment amounts. For a commercial dental payer the write-off duty comes from the participating-provider agreement, not from the two letters on the remittance, and the public X12 group-code list carries no definitional text about write-offs or patient billing at all.

Denied as not covered versus denied as bundled — which one can we bill the patient?

They are different adjustments and neither number settles the billing question on its own. A not-covered adjustment (CARC 96) must carry a remark code naming the exclusion, so the remittance should tell you which plan term was applied; whether the amount becomes a patient balance depends on the group code the payer chose and on your participation agreement. A bundled adjustment (CARC 97) says the value was already included in the allowance for another service the payer has already adjudicated — X12 places no group-code restriction on 97, so CO is the common pairing rather than a required one. In both cases the group code plus the contract decides who owes it, and a plan-stated bundle is a different appeal from a bundling edit applied to genuinely distinct services on different teeth or dates.

The patient is a Qualified Medicare Beneficiary — can we bill the deductible or coinsurance?

No. Federal law bars all Original Medicare and Medicare Advantage providers and suppliers — not only those that accept Medicaid — from billing a QMB for Medicare Part A and Part B deductibles, coinsurance, or copayments, and CMS states this holds even when Medicaid pays nothing. A QMB cannot elect to pay their way out of the protection, the protection travels with the patient across state lines, and a practice that discovers it has billed one owes a refund of what it collected and must recall any collection referral. This sits inside Medicare, so it reaches a dental practice only where the practice is Medicare-enrolled and billing Part B-covered services. If the remittance carries remark code N781, N782, or N783, note what those codes actually say: X12 classifies them as informational alerts, and their current text ends by saying the amount may be billed to a subsequent payer. The prohibition comes from the statute, not from the remark code.

Medicaid paid less than our fee — can we bill the patient the difference?

Not the difference. A state Medicaid plan must limit participation to providers who accept, as payment in full, the amounts the agency pays plus any deductible, coinsurance, or copayment the plan requires the individual to pay (42 CFR 447.15). So the gap between your fee and the Medicaid allowable is yours, while the plan's own cost sharing remains the patient's debt — that regulation also says an individual's inability to pay does not eliminate liability for the cost-sharing charge. Where a commercial payer also has liability, 42 CFR 447.20 bars collecting from the patient at all when the third party's payment equals or exceeds the state-plan amount, and limits collection to the lesser of the copay or the gap when it does not. What none of that settles is a denial: 447.15 addresses amounts the agency paid, not a claim it paid nothing on, so do not treat a Medicaid denial as an automatic write-off — check the denial reason and your state's provider manual.