File structure
An 835 has three levels:The key segments
The adjustment grammar
The core concept. Every dollar not paid is explained by a triple: Group code + CARC (+ optional RARC)Group codes, who bears the cost
Group codes affect the patient ledger. Posting a valid PR amount as CO may suppress a patient balance, while posting a CO amount as PR may bill the patient for an amount the participation agreement requires the practice to adjust. Configure auto-posting carefully and review payer-specific exceptions.
CARCs, why
Claim Adjustment Reason Codes are maintained by X12. The ones a dental biller sees constantly:
The full working set: CARC codes.
RARCs, the detail
Remittance Advice Remark Codes add detail to a CARC. For example, a RARC paired with CARC 16 may identify the missing information. In dental remittances, a RARC may also clarify the frequency rule, documentation request, or alternate-benefit rationale. See RARC codes.Reading a dental claim
Two lines from one visit: an adult prophy and a one-surface posterior composite the plan downgraded to the amalgam allowance.
Line 1 is the happy path: billed − contractual = allowed; allowed − patient share = paid, and preventive pays at 100% of allowed.
Line 2 was paid using an alternate-benefit allowance rather than the office’s composite charge. Under the example plan, the payer calculated the benefit as though an amalgam had been placed.1 Whether the remaining amount may be billed to the patient depends on the participation agreement, plan terms, applicable law, and pre-treatment disclosure. Payers represent these calculations differently, so review the allowed amount, group and reason codes, remarks, and EOB together. See Denials vs downgrades.
Frequency limits and exhausted maximums also appear as plan-benefit adjustments, often with CARC 96, 119, or 204 and a more specific RARC or EOB explanation. Confirm that the payer used the correct history, eligibility, and plan terms before accepting the result. Transfer any balance to the patient only when the contract, benefit terms, law, and financial consent permit it.
The allowed amount drives the contracted payment calculation. The contractual adjustment is the difference between the submitted charge and that allowance. Review the allowance and applicable fee schedule rather than treating the size of the write-off alone as a performance measure.
PLB, the segment that breaks reconciliation
Provider-level adjustments sit outside the claim detail and adjust the total payment. They carry:One 835 is not one bank deposit
This is an important operational feature of remittances.- One deposit can cover multiple 835s
- One 835 can be split across multiple deposits
- The PLB shifts the total away from the sum of the claims
- Paper checks and virtual credit cards arrive on entirely different timelines than the 835
Claim status codes (CLP02)
Status 4 indicates denial, status 22 indicates reversal of a prior adjudication, and status 25 identifies a predetermination response. Configure status 25 as an estimate or benefit response rather than a zero-pay claim denial.