Mich. Comp. Laws § 333.24513

Sec. 24513. This article does not prohibit a nonparticipating provider and a carrier from agreeing, through private negotiations or an internal dispute resolution process, to a payment amount that is greater than the amounts described in section 24507(2) or 24509(5). A nonparticipating provider entering into an agreement authorized under this section shall not collect or attempt to collect from the patient any amount other than the applicable in-network coinsurance, copayment, or deductible.