S.D. Codified Laws § 58-15-44
No insurer may knowingly deliver or issue for delivery in this state any life insurance policy that purports to be issued or to take effect as of a date more than six months before the application therefor was made, if thereby the premium on the policy is reduced below the premium that would be payable thereon as determined by the insuring age of the insured at the time when such application was made. No insurance producer or other representative of an insurer may in this state prepare, submit, or accept any application for life insurance that bears a date earlier than the date when the application was made by the insured or applicant, if thereby the premium on the contract is reduced as above stated. Nothing contained in this section invalidates any contract made in violation of this section. This section does not prohibit the exchange, alteration, or conversion of any policy of life insurance.
SDCL 58-15-44