With respect to wages paid after April 30, 1975, the amount of tax to be deducted and withheld under the percentage method of withholding shall be determined under the applicable percentage method withholding table contained in Circular E (Employer's Tax Guide) according to the instructions contained therein.
(Secs. 3402(i) and (m) and 7805 of the Internal Revenue Code of 1954 (26 U.S.C. 3402 (i) and (m), 95 Stat. 172, 184; 26 U.S.C. 7805, 68A Stat. 917))