S.D. Codified Laws § 58-16-11
The premium for a policy issued under § 58-16-7 shall be paid by the policyholder, either wholly from the union's funds, or partly from such funds and partly from funds contributed by the insured members specifically for their insurance. No policy may be issued on which the entire premium is to be derived from funds contributed by the insured members specifically for their insurance. A policy on which part of the premium is to be derived from funds contributed by the insured members specifically for their insurance may be placed in force only if at least seventy-five per cent of the then eligible members, excluding any as to whom evidence of individual insurability is not satisfactory to the insurer, elect to make the required contributions. A policy on which no part of the premium is to be derived from funds contributed by the insured members specifically for their insurance must insure all eligible members, or all except any as to whom evidence of individual insurability is not satisfactory to the insurer.
SDCL 58-16-11