An active participant's monthly accrued benefit as of any date, subject to the modifications below, will be equal to the product of (1) and (2) as follows:
An active participant's monthly accrued benefit may not be less than the amount of the participant's monthly retirement benefit accrued as of December 11, 1984.
After all other modifications have been applied, an active participant's monthly accrued benefit shall be reduced by the amount of deferred monthly retirement benefit under the normal form beginning on the normal retirement date in lieu of which the participant has received a single sum payment under the plan. The participant's accrued benefit resulting from employer contributions is equal to the participant's total accrued benefit reduced by the required contribution accrued benefit.
SDCL 3-13C-15