I did some checking on this, and am thinking the withholding amount may be correct even tho the report shows the 6 for the particular employee in questions federal withholding.    Here's how I checked it.   I have two employees that have the same gross wages.  They are both single/married filing separately. On the withholding report, the 2nd employee shows 0 in the federal withholding column and the 1st employee has a 6.     The 2nd employee normally asks for additional withholding out of his paycheck. I changed his additional withholding to match the other employee and ran a mock payroll and their net pay was the same.   So my guess is that the number in the federal withholding column no longer affects the actual withholding amount.