Mass. Gen. Laws ch. 32, § 103
(i) Notwithstanding the provisions of paragraph (c) to the contrary, the board of any system may, by accepting the provisions of this as hereinafter provided, elect annually to pay a cost-of-living increase greater than the percentage increase, as recommended in the report prepared in accordance with paragraph (f) of subdivision (3) of section 21 for that year, but not greater than 3 per cent. The board shall conduct such election in a public meeting, properly posted, called specifically for such election. The board shall also notify each legislative body at least 30 days before such election.
Acceptance of this subsection shall be by a majority vote of the board of such system, subject to the approval of the legislative body. For the purpose of this section, ''legislative body'' shall mean, in the case of a city, the city council in accordance with its charter, in the case of a town, the town meeting, in the case of a county, the county retirement board advisory council, in the case of a district, the district members, and, in the case of an authority, the governing body. Acceptance of this subsection shall be deemed to have occurred upon the filing of the certification of such vote with the commission. A decision to accept the provisions of this subsection may not be revoked.