Amending the act of March 4, 1971, entitled "An act relting to tax reform and State taxationand imposing taxes thereon; providing procedures for the payment, collection, administration, and enforcement thereof; providnig for tax credits in certain cases; conferring powers and imposing duties upon the Department of Revenue, certain employers, fiduciaries, individuals, persons, corporations, and other entities; prescribing crimes, offenses and penalties, "providing for a free medical clinic tax credit."