(1) Reimbursement for inpatient hospital services is set forth in ARM 37.86.2806, 37.86.2905, 37.86.2907, 37.86.2910, 37.86.2912, 37.86.2916, 37.86.2918, 37.86.2920, 37.86.2924, 37.86.2925, 37.86.2928, 37.86.2943, and 37.86.2947. Reimbursement for outpatient hospital services is set forth in ARM 37.86.3005, 37.86.3006, 37.86.3007, 37.86.3009, 37.86.3014, 37.86.3016, 37.86.3018, 37.86.3020, 37.86.3022, 37.86.3025, 37.86.3037, and 37.86.3109. Cost of hospital services will be determined for inpatient and outpatient care separately. Administratively necessary days are not a benefit of the Montana Medicaid program.

(2) The department may require providers of inpatient or outpatient hospital services to obtain authorization from the department or its designated review organization either prior to provision of services or prior to payment.

(3) Medicaid reimbursement shall not be made unless the provider has obtained authorization from the department or its designated review organization prior to providing any of the following services:

(a) inpatient psychiatric services provided in an acute care psychiatric hospital, acute care general hospital or a distinct part psychiatric unit of an acute care general hospital, as required by ARM 37.88.101;

(b) except as provided in (4) all inpatient services provided in preferred hospitals located more than 100 miles outside the borders of the state of Montana;

(c) services related to organ transplantations covered under ARM 37.86.4701 and 37.86.4705; or

(d) outpatient partial hospitalization, as required by ARM 37.88.101.

(e) any other services for specific diagnosis or procedures that require all Medicaid providers to obtain prior authorization; or

(f) facilities designated as a Center of Excellence.

(4) Upon the request of a preferred hospital, the department may grant retroactive authorization for the provision of the hospital's services under the following circumstances only:

(a) the person to whom services were provided was determined by the department to be retroactively eligible for Montana Medicaid benefits including hospital benefits;

(b) the hospital is retroactively enrolled as a Montana Medicaid provider, and the enrollment includes the dates of service for which authorization is requested;

(c) the hospital can document that at the time of admission it did not know, or have any basis to assume, that the patient was a Montana Medicaid client; or

(d) the hospital can document that the admission was an emergency admit for purposes of stabilization or stabilization for transfer. The hospital must call for authorization within two working days (Monday through Friday) of the admission.