Section 35SS. There shall be established and set up on the books of the commonwealth a separate fund to be known as the Build America Bonds Subsidy Trust Fund, in this section called the fund. There shall be credited to the fund payments received from the United States Treasury for subsidies related to any tax credit bonds issued by the commonwealth for the purpose of paying or reimbursing interest on such bonds. The state treasurer shall be the fund’s trustee, may credit any such payments to the appropriate funds or accounts of the commonwealth allocable to the payment of such interest and in accordance with any applicable trust agreements pursuant to which any bonds were issued and shall make expenditures from the fund, without further appropriation, to pay debt service related to such bonds. The comptroller may, without further appropriation, transfer from any available appropriation any amount determined by the comptroller to have been withheld by the federal government from a tax credit bond subsidy payment.