(1) For purposes of this section:

(a) Nonreimbursable expenditure means an expenditure included within the total allowable excess cost for all special education programs and support services as submitted to the department on or before the first October 31 following the school fiscal year in which the expenditure occurred that is later determined to be nonreimbursable as a special education program or support services expenditure; and

(b) Three-year average nonreimbursable expenditures means the average total nonreimbursable expenditures for all school districts for the most recent three school fiscal years for which such information is available.

(2)(a) For each fiscal year, the aggregate amount appropriated from the General Fund and the Education Future Fund for special education programs and support services pursuant to sections 79-1129, 79-1132, and 79-1144 shall not be less than the amounts required pursuant to section 79-1142 to (i) reimburse residential settings described in subdivision (10)(c) of section 79-215 for educational services and reimburse eighty percent of the total allowable excess costs for all special education programs and support services or (ii) meet federal maintenance of state financial support requirements, whichever is greater.

(b) The amount required to reimburse eighty percent of the total allowable excess costs for all special education programs and support services shall be calculated by subtracting eighty percent of three-year average nonreimbursable expenditures from eighty percent of the total allowable excess costs for all special education programs and support services as submitted to the department on or before the first October 31 following the school fiscal year in which the allowable excess costs occurred.