Mass. Gen. Laws ch. 29 § 2I
There shall be established and set up on the books of the commonwealth a separate fund to be known as the Tax Reduction Fund, consisting of amounts transferred to the fund under section 2H and income derived from the investment of amounts so transferred. The purpose of the fund shall be to maintain a reserve which shall be used only to reduce personal income taxes as provided in this section.
On or before October 31, the comptroller shall certify to the governor the total amount in the Tax Reduction Fund as shown in the financial report of the comptroller for the preceding fiscal year. A temporary increase in the amounts of the personal exemption allowable on the income tax shall be provided, subject to appropriation, for the taxable year ending on the succeeding December 31 to the extent that the amount in the Tax Reduction Fund equals an integer multiple of 5 per cent of the amount of the personal income taxes which will not be collected for said taxable year on account of such personal exemptions. The commissioner of revenue shall calculate the amount of the temporary increase, if any, in such personal exemptions for said taxable year. The comptroller shall transfer the amount equal to such integer multiple of 5 per cent of the amounts not collected due to such personal exemptions from the Tax Reduction Fund to the General Fund.
Mass. Gen. Laws ch. 29, § 2I