# CO 45 denial code on dental claims > What does denial code CO 45 mean on a dental claim, and can it be appealed? URL: https://dentovio.com/dental-claim-denial-codes/co-45 Last verified: 2026-08-29 Dentovio is an independent publisher — not a payer, the ADA, X12, or any government agency. Code meanings on this page are Dentovio's paraphrases of the X12 Claim Adjustment Reason Code list (the official descriptions are published by X12 and are its copyrighted work); appealability verdicts are editorial guidance grounded in payer-filed denial data and published payer policies. Educational billing reference only — not billing, legal, or clinical advice. Plan contracts control individual outcomes. ## Direct answer On a dental remittance, code CO 45 means: The billed charge exceeds the fee schedule, maximum allowable, or contracted rate — the amount above the allowed rate is adjusted off. depends: check the facts first. The adjustment itself is contractual. What is contestable is the underlying fee schedule: if the allowed amount does not match your contracted schedule, request the fee schedule the claim was priced against and dispute the pricing — that is an underpayment dispute, not a benefits appeal. ## What it means in dental context On in-network dental claims this is the ordinary contractual write-off, not a denial. It matters when it appears unexpectedly large: a wrong fee schedule attached to your contract, a leased-network rate you did not know governed the claim, or a payer processing under the wrong network tier. ## Appealability: Depends — check the facts first Contractual variants of this denial are final; factual-error variants are winnable. Run the checks on this page before spending the appeal window. The adjustment itself is contractual. What is contestable is the underlying fee schedule: if the allowed amount does not match your contracted schedule, request the fee schedule the claim was priced against and dispute the pricing — that is an underpayment dispute, not a benefits appeal. ## What to do 1. Compare the allowed amount on the ERA against your contracted fee schedule for that CDT code 2. If they differ, ask the payer in writing which network/lease priced the claim 3. Track underpayment-dispute windows — several states cap them (Florida: 12 months) ## Official source - X12 Claim Adjustment Reason Codes (official descriptions): - HIPAA adoption of the 835 remittance standard that carries these codes (45 CFR 162.1602): ## Related - [All dental denial codes](https://dentovio.com/dental-claim-denial-codes/index.html.md) - [Payer documentation requirements](https://dentovio.com/dental-claim-documentation/index.html.md) - [Dental insurance prompt-pay laws by state](https://dentovio.com/dental-prompt-pay-laws/index.html.md)