S.D. Codified Laws § 58-17-17
There shall be a provision as follows: "Grace period: A grace period of __________ (insert a number not less than seven days for weekly premium policies, ten days for monthly premium policies and thirty-one days for all other policies) days will be granted for the payment of each premium falling due after the first premium, during which grace period the policy shall continue in force." If a claim arises under the policy during such period of grace the amount of any proportionate premium due or overdue for the grace period may be deducted from the policy proceeds but such deduction shall not renew the policy or further extend the grace period. Claims arising during a grace period shall be compensable whether or not a renewal premium has been tendered or accepted subject to any other policy defenses.
A policy which gives the policyholder the right to select any one of two or more modes of premium payment by remitting an amount stated in the policy for that particular mode of payment, without requiring any formal request on the part of the policyholder for changing the mode of premium payment, shall provide a grace period of thirty-one days.
SDCL 58-17-17