§ 73. Abandonment of plan. The board of supervisors of a county may by local law provide for the abandonment of a plan, effective as of the close of the calendar year then in progress. Such plan, however, shall continue to operate thereafter until all liabilities of the plan incurred prior to such effective date shall have been satisfied and all advances to the county self-insurance fund shall have been repaid. Such local law shall provide a method for the distribution of any assets of the plan remaining after all such liabilities have been satisfied. The provisions of this section shall not apply to any plan abandoned pursuant to section sixty-one of this chapter. At the discretion of the chair, the board of supervisors of a county may execute an assumption of workers' compensation liability insurance policy securing such further and future contingent liability as may arise from prior injuries to workers and be incurred by reason of any change in the condition of such workers warranting the board making subsequent awards for payment of additional compensation. Such policy shall be in a form approved by the superintendent of financial services and shall be issued by the state fund or any insurance company licensed to issue this class of insurance in this state. In the event that such policy is issued by an insurance company other than the state fund, then said policy shall be deemed to be of the kind specified in paragraph fifteen of subsection (a) of § 1113 of the insurance law and covered by the workers' compensation security fund as created and governed by article six-A of this chapter. It shall only be issued for a single complete premium payment in advance by the county, city, village, town, school district, fire district or other political subdivision of state and in an amount deemed acceptable by the chair and the superintendent of financial services. In lieu of the applicable premium charge ordinarily required to be imposed by a carrier, said premium shall include a surcharge in an amount to be determined by the chair to satisfy all assessment liability due and owing to the board and/or the chair under this chapter. Said surcharge shall be payable to the board simultaneous to the execution of the assumption of workers' compensation liability insurance policy. However, the payment of said surcharge does not relieve the carrier from any other liability, including liability owed to the superintendent of financial services pursuant to article six-A of this chapter. When issued such policy shall be non-cancellable without recourse for any cause during the continuance of the liability secured and so covered.