The following hospitals are exempt from any assessment under this chapter provided that if and to the extent any exemption is held invalid by a court of competent jurisdiction or by the centers for medicare and medicaid services, hospitals previously exempted shall be liable for assessments due after the date of final invalidation:

(1) Hospitals owned or operated by an agency of federal or state government, including but not limited to western state hospital and eastern state hospital;

(2) Washington public hospitals that participate in the certified public expenditure program;

(3) Hospitals that do not charge directly or indirectly for hospital services; and

(4) Long-term acute care hospitals.