Mass. Gen. Laws ch. 149, § 198: Professional employer agreements; taxes, assessments or mandated expenditures on per capita or per employee basis, or upon total payroll basis

Section 198. (a) A tax assessed or an assessment or a mandated expenditure on a per capita or per employee basis shall be assessed against the client for covered employees and against the PEO for its employees who are not covered employees involved in a PEO relationship with a client. Benefits or monetary consideration that meet the requirements of mandates imposed on a client and that are received by covered employees through the PEO through payroll or through benefit plans sponsored by the PEO shall be credited against the client's obligation to fulfill such mandates.

(b) If there is a tax or an assessment imposed or calculated upon the basis of total payroll, the PEO shall be eligible to apply any small business allowance or exemption available to the client for the covered employees for purpose of computing the tax.