(1) Case management services for adults with severe disabling mental illness will be reimbursed on a fee per unit of service basis as follows. For purposes of this rule, a unit of service is a period of 15 minutes.

(a) The department will pay the lower of the following for case management services:

(i) the provider's actual submitted charge for services; or

(ii) the amount specified in the department's Medicaid fee schedule.

(2) The department may, in its discretion, designate a single provider of case management services in a designated geographical region. Any provider designated as the sole case management provider for a designated geographical region must, as a condition of such designation, agree to serve the entire designated geographical region.