Mass. Gen. Laws ch. 30 § 24B
Whenever an employee in a lower grade is assigned the duties of a position in a higher grade for a period of thirty days or longer, the appointing officer shall, if a vacancy exists or is to exist for the position in the higher grade, forthwith submit to the personnel administrator a requisition for approval of the appointment of such employee to such position. The approval of said administrator of such an appointment shall, if given, take effect as of the earliest date, as determined by the administrator, that he could have approved the appointment if acted upon by him on the date the appointment was made, but in no case shall he approve an appointment to take effect earlier than sixty days next preceding the date of the receipt of said requisition by him.
This section shall not apply to assignment of a person to cover a higher position when the holder of the higher grade position is absent on vacation leave, but shall apply when the holder of such higher graded position is on sick leave.
Mass. Gen. Laws ch. 30, § 24B