Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 152, § 35

While the incapacity for work resulting from the injury is partial, during each week of incapacity the insurer shall pay the injured employee a weekly compensation equal to sixty percent of the difference between his or her average weekly wage before the injury and the weekly wage he or she is capable of earning after the injury, but not more than seventy-five percent of what such employee would receive if he or she were eligible for total incapacity benefits under section thirty-four. An insurer may reduce the amount paid to an employee under this section to the amount at which the employee's combined weekly earnings and benefits are equal to two times the average weekly wage in the commonwealth at the time of such reduction.

The total number of weeks of compensation due the employee under this section shall not exceed two hundred sixty; provided, however, that this number may be extended to five hundred twenty if an insurer agrees or an administrative judge finds that the employee has, as a result of a personal injury under this chapter, suffered a permanent loss of seventy-five percent or more of any bodily function or sense specified in paragraph (a), (b), (e), (f), (g), or (h) of subsection (1) of section thirty-six, developed a permanently life-threatening physical condition, or contracted a permanently disabling occupational disease which is of a physical nature and cause. Where applicable, losses under this section shall be determined in accordance with standards set forth in the American Medical Association Guides to the Evaluation of Permanent Impairments. Where the insurer agrees or the administrative judge finds such permanent partial disability as is described in this paragraph, the total number of weeks the employee may receive benefits under both this section and section thirty-four shall not exceed five hundred twenty. Where there has been no such agreement or finding the number of weeks the employee may receive benefits under these sections shall not exceed three hundred sixty-four.