Section 94M. All unused or unabsorbed portions of premium deposits at exchanges returned or credited to subscribers shall be subject to all provisions of this chapter and chapter one hundred and fifty-two relating to the payment of dividends by mutual companies including therein the provisions of sections eighty, one hundred and thirteen B, one hundred and eighty-two, one hundred and eighty-three and one hundred and eighty-four of this chapter and section fifty-three of said chapter one hundred and fifty-two relating to rates of return, classifications and rebates, except that the amount of the unused or unabsorbed portion of the premium deposit credited or returned to the subscriber shall be determined under the terms and conditions of the power of attorney or subscriber's agreement.