Within fifteen days after the end of a calendar quarter or such other period as determined by the department, the department shall bill the state for an amount equal to the full amount of benefits including, prior to December 31, 1978, one-half of the amount of extended benefits, and thereafter, the amount of extended benefits, if any, paid during such quarter or other prescribed period that is attributable to service in the employ of the state.
SDCL 61-5A-2