S.D. Codified Laws § 58-15-43.6

The recalculated nonforfeiture net level premium is equal to the result obtained by dividing (A) by (B) if (A) equals the sum of the nonforfeiture net level premium applicable prior to the change times the present value of an annuity of one per annum payable on each anniversary of the policy on or subsequent to the date of the change on which a premium would have fallen due had the change not occurred, and the present value of the increase in future guaranteed benefits provided for by the policy, and (B) equals the present value of an annuity of one per annum payable on each anniversary of the policy on or subsequent to the date of change on which a premium falls due.