Mass. Gen. Laws ch. 149 § 150A
Every person making a deduction from wages of any employee for social security, unemployment compensation benefits, pension, vacation or health and welfare funds, state taxes, federal taxes, dues check-off and credit unions and every person engaged in contracting or sub-contracting, highway or building construction projects or public works construction who is party to an agreement to make contributions for unemployment compensation benefits, pension, vacation or health and welfare funds, apprentice training programs, federal tax, state tax, dues check-off or contributions to a credit union for the benefit of any employee, or who is required to make such contributions to such funds or programs or payments directly to an employee under the provisions of section twenty-seven, and which contributions or payments are computed on an hourly, daily, weekly or monthly basis, shall furnish each such employee a suitable pay slip, check stub or envelope, notifying such employee of the amount of each such deduction or contribution at the time of the payment of wages from which such deduction is made and in the case of a contribution at the time when such contribution is made; provided, however, that a new employee shall be notified in writing at the time of the first payment of his wages about the nature of such deduction or contribution; and provided, further, that each such employee shall be notified in writing at the initial time of any new deduction or contribution from the wages about the nature of such deductions and contributions.
Mass. Gen. Laws ch. 149, § 150A