Claims · Updated 2026-09-08 · 5 min read

How do I read a dental EOB?

Read every EOB line in one order: billed, allowed, plan paid, patient responsibility, then the group code, then the remark code that carries the actual rule.

Read every line of an Explanation of Benefits in the same order, every time: the billed fee, the allowed amount, what the plan paid, and what is left as patient responsibility. Then read the two codes, and read them in the right order. The group code — CO, PR, OA or PI — comes first, because it says whose money the unpaid difference is. The Claim Adjustment Reason Code (CARC) is the money code that says why the plan paid less than the fee. The Remittance Advice Remark Code (RARC) moves no money at all, and on a dental EOB it is usually the only place the rule the carrier actually applied is written down. As of September 2026, one of the two most-printed code tokens on the dental remittance lines we measured was CARC 45, on 8,951 lines across 51 different payers — and CARC 45 is not a denial. It is the in-network write-off, and it rides paid lines.

What we measured

Code tokens printed on dental EOB lines, all carriers, measured September 2026. Only tokens seen at five or more practices are counted. The payers column is how many distinct insurance companies printed that token.

The payer count is the single most useful column on that table. A code printed by dozens of different insurance companies is an X12 code, and any published list decodes it. A code printed by one or two companies is that carrier's private library, and only that carrier's own legend decodes it. That is why 16 is marked ambiguous: 1,928 lines across 33 practices but only 10 payers, which is the fingerprint of a private library rather than the national code set.

What the carriers' own documents say

Delta Dental writes the "who owes it" answer into the description of the code itself. Policy code 515, its alternate-benefit code, reads verbatim:

"This service is not a covered benefit of the enrollee's program because there is a less expensive, professionally acceptable alternative treatment available. We have applied an alternate procedure number and allowance to ensure accurate processing. The patient is responsible for the amount indicated as 'Patient Pays.'"

(Delta Dental – Policy ID Mapping for CARC/RARC Health Care Policy Codes, Delta Dental of California provider reference.)

MetLife states the ceiling that survives any denial, in its MetLife Preferred Dentist Program (PDP) Resource Manual:

"Whenever a participant receives any services from a participating dentist, the plan allowance applies. When the plan allowance is not reimbursed in full or in part by the benefit plan, any difference is the responsibility of the participant up to the plan allowance. The participant is not responsible for any amount that exceeds the plan allowance."

Plain words: when a covered service is denied on a PR line on a participating dentist's claim, the patient owes the contracted allowance, not the office's full fee.

Why it depends on the contract

The same denial can carry a different group code depending on whether the dentist is in the network, and Delta Dental publishes both columns side by side. Its policy code 455 — a filling within six months of a crown — is PR (bill the patient) for a non-participating dentist and PI (write it off) for a participating one. So is 504, and so is 718. Codes 503 and 515 are PR both ways. The code did not change; the contract did.

Two more reading traps sit on the same page:

• A plan provision quoted on the EOB is not proof it was applied. Guardian's noble-metal alternate-benefit sentence appeared on 105 measured lines, and 86 of those lines were paid in full. The identical wording sits on lines that were downgraded and lines that were not. Check the money, not the sentence.
• The claim's status word is not the line's outcome. On measured Cigna lines carrying the identical NT code, 656 read "Processed" and 92 read "Denied". The code was stable and the status word was not.

What to do

• Read the columns left to right and stop at patient responsibility. If billed minus allowed is the whole difference and the plan paid its share, there is no denial on that line — that gap is CARC 45 and it is the contractual write-off.
• Read the group code before the reason code. CO and PI mean the patient may not be billed. PR means they may. OA usually means another carrier's payment moved the money.
• When the reason code is 96, treat it as a money bucket, not a reason. X12 requires a remark code beside it, and the remark is where the actual rule lives — a waiting period, a missing tooth limitation, a frequency cap, a bleaching limit.
• When the remark is N130 — consult the plan benefit documents for restrictions on this service — the carrier has told you a rule exists and nothing else. Look the rule up before you write anything to the patient's ledger.
• Do not assume a code means a denial. Check the paid amount on the line first; on some carriers' remittances a reason code rides an approved, paid line as an informational note.
• Record the group code alongside the reason in the ledger note, because that is the field the next person needs when the patient calls to ask why they owe it.

Numbers last refreshed September 2026.

All articles · Kaylie