N.M. Admin. Code § 8.302.2.12
To receive payment for services furnished to an eligible recipient or member who is also entitled to medicare, a provider must first bill the appropriate medicare payer. The medicare payer pays the medicare covered portion of the bill. After medicare payment, MAD pays the amount the medicare payer determines is owed for co-payments, co-insurance and deductibles, subject to MAD reimbursement limitations. If a medically necessary service is excluded from medicare and it is a MAD covered benefit, MAD will pay for service. When the medicare payment amount exceeds the amount that MAD would have allowed for the service, no further payment is made for the coinsurance, deductible, or co-payment. The claim is considered paid in full. The provider may not collect any remaining portion of the medicare coinsurance, deductible, or co-payment from the eligible recipient or their authorized representative. For behavioral health professional services for which medicare part B applies to a "psych reduction" to the provider payment and increases the eligible recipient or member coinsurance rate, medicare coinsurance and deductible amounts are paid at an amount that allows the provider to receive eighty percent of the medicare allowed amount even if such amount exceeds the MAD allowed amount for the service. A provider must accept assignment on medicare claims for MAD eligible recipients and members. A provider who chooses not to participate in medicare or accept assignment on a medicare claim must inform the MAD eligible recipient, member or his or her authorized representative that the provider is not a medicare provider or will not accept assignment; and because of those provider choices, MAD cannot pay for the service. Additionally, the provider must inform the eligible recipient, member or his or her authorized representative of the estimated amount for which the eligible recipient or member will be responsible, that service is available from other providers who will accept assignment on a medicare claim, and identify an alternative provider to whom the eligible recipient or member may seek services. The provider cannot bill a dually eligible MAP recipient or member for a service that medicare cannot pay because the provider chooses not to participate in medicare, or which MAD cannot pay because the provider chooses not to accept assignment on a claim, without the expressed consent of the eligible recipient, member or his or her authorized representative even when the medicare eligibility is established retro-actively and covers the date of service.
N.M. Admin. Code § 8.302.2.12