Beginning in fiscal year 2027-28, and for each subsequent fiscal year, the commissioner shall make a regional adjustment in the total operating allocation for each school administrative unit determined pursuant to section 15683. The regional adjustment must be based on the regional differences in the cost of living, as computed by a statewide education policy research institute using a nationwide index or combination of nationwide indices. The regional adjustment must align with the salary matrix described in section 15677 so that the minimum index value is sufficient to pay the minimum teacher salary established under chapter 505. The regional adjustment must be applied only to appropriate teacher salary and benefit costs as calculated under section 15678 and salary costs of other school-level staff who are not teachers as calculated under section 15679.   [PL 2025, c. 737, §4 (NEW).]