In the event that a Compact member state withdraws from the Compact before June 30, 1994, any person in such Compact member state who has made voluntary contributions shall be entitled to a refund of such contributions, not to include any actual interest earned on such contributions. The department may, pursuant to section 303,¹ impose additional fees on mandated contributors sufficient to provide the amount to be refunded. This refund shall be paid when such additional fees become available to the department.