SDCL § 4-8-21: Reversion of unencumbered special appropriations after four years--Period of availability of encumbered amounts.

At the end of four full fiscal years following the effective date of any special appropriations act, unless such act explicitly states to the contrary, the amount of the appropriation remaining unexpended and which has not been contractually obligated in writing, and approved by the commissioner of finance and management prior to the end of the fiscal year, shall lapse and cease to be available, and revert to the fund from which appropriated. Such encumbered amounts shall be only available for such expenditure for a period of not to exceed two additional fiscal years as determined by the commissioner of finance and management.