Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 151A, § 3

(a) the service is localized in the commonwealth. Service shall be deemed to be localized within the commonwealth if the service is performed entirely within the commonwealth, or the service is performed both within and without the commonwealth, but the service performed without the commonwealth is incidental to the individual's service within the commonwealth; for example, is temporary or transitory in nature, or consists of isolated transactions.

(b) the service is not localized in any state, but some part of the service is performed in the commonwealth and (1) the individual's base of operations is in the commonwealth or, if there is no base of operations, then the place from which such service is directed or controlled, is within the commonwealth, or (2) the individual's base of operations or place from which such service is directed or controlled is not in any state in which some part of the service is performed, but the individual's residence is in the commonwealth.