Verdict
Structural — verify the plan terms
The denial reflects a plan term such as an exclusion or exhausted limit. Verify that the payer used the correct plan and facts before deciding how the contract assigns responsibility.
Both plans' terms would have to change for this to pay. What is worth verifying is that both were actually adjudicated, and against the right plans — a stale plan on either side produces this result wrongly.
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.