SDCL § 8-10-9: Proration of appropriations for more than one year.

In all cases where appropriations of money have heretofore or may hereafter be made for periods longer than one year, it shall be unlawful for the person or persons whose duty it is to expend such appropriation, to audit, expend, or contract to pay more money in any one year than a pro rata share thereof; that is, the expenditures for one year shall never exceed the proportion which one year of time bears to the whole time, unless otherwise expressly provided.