(a) Unless otherwise provided by law, each town shall elect a board of assessment appeals consisting of three members and shall elect such officers at regular municipal elections for terms of four years. Such members of the board of assessment appeals shall hold office for the term for which they are elected and until their successors are elected and have qualified. When the number of members of the board of assessment appeals to be elected by any town is even, no person shall vote for more than one-half the number, and when the number to be elected is odd, no person shall vote for more than a bare majority of the number, provided the legislative body of any town may provide that the electors of such town vote for the full number of members to be elected thereat, any provision of the special acts to the contrary notwithstanding. The candidates in number sufficient to fill such offices who have the highest number of votes shall be elected. Nothing in this section shall be construed to affect the method of rotation of members of a board of assessment appeals legally in effect on October 1, 1976.

(b) The legislative body of a municipality or, in the case of a municipality for which the legislative body is a town meeting or a representative town meeting, the board of selectmen may appoint an alternate for each member of the board of assessment appeals. Each alternate member shall be an elector of the municipality. When seated, an alternate member shall have all the powers and duties of a member of the board of assessment appeals.

(c) Notwithstanding the provisions of subsection (a) of this section or of any special act, municipal charter or home rule ordinance, a municipality may, by ordinance, authorize its legislative body to appoint additional members to the board of assessment appeals for any assessment year.