This is a great topic. It isn't something that comes up terribly often but when it does it is always a debate. I know it goes by COB method but I'm still hung up on the fact that the secondary is saying $0 PR.
Total charges $110: BCBS (primary): Allowable $45 (went towards deductible) - Patient Responsibility $85 - Paid $0 1199-Aetna (secondary): Allowable $35 - Patient Responsibility $0 - Paid $35