The policy may also provide that if interest on any indebtedness is not paid when due it shall then be added to the existing indebtedness and shall bear interest at the same rate, and that if and when the total indebtedness on the policy, including interest due or accrued, equals or exceeds the amount of the loan value thereof, then the policy shall terminate and become void but not until at least thirty days' notice shall have been mailed by the insurer to the last known address of the insured or policy owners and of any assignee of record at the home office of the insurer.
SDCL 58-15-19