Mass. Gen. Laws ch. 62F § 6
If net state tax revenues in any fiscal year exceed allowable state tax revenues for said fiscal year the amount of such excess, as determined by the State Auditor and reported to the Commissioner pursuant to section five of this chapter, shall result in a credit equal to the total amount of such excess. The credit shall be applied against the then current personal income tax liability of each taxpayer who files an income tax return in both the then current and the previous taxable year in an amount determined by dividing the total amount of excess revenues by the total number of taxpayers filing an income tax return in the previous taxable year. For the purposes of this section, a married couple filing a joint return shall be counted as 2 taxpayers. If the amount of the credit allowed under this section exceeds the taxpayer's liability, the commissioner shall treat the excess as an overpayment and shall pay the taxpayer the amount of the excess without interest.
The Commissioner shall take such action and shall have the authority to issue such rules and regulations as are necessary to effectuate the requirements of this section.
Mass. Gen. Laws ch. 62F, § 6