An Act amending the act of August 24, 1961 (P. L. 1135, No. 508), entitled "An act imposing a tax for general public school purposes in school districts of the first class A on salaries, wages, commissions and other compensation earned by residents thereof, ***; providing for the administration and enforcement of the act and imposing penalties for violation thereof," further providing for the withholding procedure by employers of taxes and increasing the interest and penalties assessed for late payments.