I am hoping this community can help. There are several bill audit vendors out there that will recommend that an ERISA plan or Stop Loss Carrier deny line items from a bill. Unbundling is a common denial reason. These recommendations are based on CMS guidelines, not the terms of the commercial contract, the payer's reimbursement policies or plan document. When challenged, their response is "CMS guidelines dictate that providers bill in the same manner for both Medicare and commercial claims". Where is this written?