Section 40. The compensation of each teacher, except a person in training and except a person employed as a temporary substitute, upon a majority vote of the respective school committee and the appropriating authority or, in the case of a regional school district, upon acceptance as provided hereafter, shall be at a rate of not less than eighteen thousand dollars or at a rate not less than twenty thousand dollars, as designated by said vote, for the school year commencing after July first, nineteen hundred and eighty-seven. In the case of a regional school district, acceptance shall require the approval of the regional school district committee and two-thirds of the appropriating authorities of the municipalities in such regional school district. The compensation paid to such teachers shall be deemed to be fully earned at the end of the school year, and proportionately earned during the school year. Payment of such compensation may be deferred to the extent that equal payments may be established for a twelve month period including amounts payable in July and August subsequent to the end of the school year. Educational collaboratives, formed under the provisions of section four E of chapter forty, may accept the provisions of this section by a majority vote of the collaborative board and the approval by a vote of the majority of the appropriating authorities of the member cities and towns.

Any city, town, regional school district, educational collaborative or independent vocational school district which currently employs teachers at salaries below eighteen thousand dollars or below twenty thousand dollars and which accepts the minimum salary provisions of this section for school years commencing after July first, nineteen hundred and eighty-seven shall receive a minimum teacher salary grant from the commonwealth in fiscal years nineteen hundred and eighty-eight and nineteen hundred and eighty-nine equal to the cost incurred by such city, town, collaborative or regional school district during said fiscal years as a result of increasing the minimum teacher salary to eighteen thousand dollars or to twenty thousand dollars, as designated by the vote of the school committee and the appropriating authority thereof, for each teacher whose salary was below that level prior to July first, nineteen hundred and eighty-seven and for each teacher hired after June thirtieth, nineteen hundred and eighty-seven whose salary was below that level at any time between July first, nineteen hundred and eighty-seven and June thirtieth, nineteen hundred and eighty-nine.