Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 59, § 5J

A city or town, by adoption of an ordinance or by-law, may establish a special assessment policy for the substantial rehabilitation of owner-occupied residential properties listed in the state register of historic places, either individually or as contributing elements within an historic district. For such properties, the increase in assessed value resulting from such rehabilitation shall be phased in one-fifth increments over a period of five years to the full assessed value of the property; provided, however, that the rehabilitation shall meet the standards of the Massachusetts historical commission in order to be eligible for the phased in special assessment; and provided further, that the secretary of the commonwealth, as chairman of the Massachusetts historical commission, shall promulgate applicable rules and regulations to carry out the provisions of this section.