An insurer may accept, from a holder of a life insurance policy, deposits in addition to current premium payments to provide a fund for payment of future premiums or to make possible the future acquisition of additional insurance, annuities or other benefits, whether the interest to be paid on such deposits be fixed or variable. Such deposits, or any portion thereof, not used for the purposes described in this section shall be refunded to the policyholder or, upon the death of the policyholder, to designated beneficiaries. [1967 c.359 § 96]