(a) Any corporation organized for manufacturing purposes, for laundering, or for the processing and curing of meats, their products, and by-products, which by the act of May sixteenth, one thousand nine hundred and thirty-five (Act Number eighty-six),¹ is required to pay a tax on its capital stock or a franchise tax upon a taxable value of its capital stock, and (b) any corporation which by the act of May sixteenth, one thousand nine hundred and thirty-five (Act Number ninety-one),² is required to pay an excise tax on net income, and (c) any corporation which by the act of May sixteenth, one thousand nine hundred and thirty-five (Act Number eighty-nine),³ is required to pay an increased tax on gross receipts derived wholly from business done within this State, shall have authority to pay such taxes or such increased taxes, as the case may be, or any part thereof, into the treasury of the Commonwealth through the Department of Revenue in advance of the due date thereof and be entitled to receive a discount of four per centum (4%), per annum, on the amount so paid, which discount shall be calculated from the date of the advance payment to the date when such taxes actually become due, as ascertained by reference to the date when such taxes are actually settled and the time allowed by law for payment after settlement or the date fixed by law for payment, as the case may be.