First, go into Maintain Employees and check the employee's pay frequency (on the Pay Info tab) and W-4 settings (on the Withholding Info tab). If they get paid weekly but their pay frequency is set to Monthly or Annually, it makes it look like their pay is low enough to have no withholding. With today's withholding table, it's also common for lower paid employees to have no withholding.

Once you have checked those things, enter a paycheck with much higher than normal pay and see if it calculates any federal withholding. If it does, then you know all the formulas are in place. Also, go to https://www.paycheckcity.com/calculator and calculate a paycheck to see if it matches what you're getting in Sage 50. Make sure you set the pay method, pay frequency, and W4 info exactly like it is in Sage 50. If you get the same result here as you get in Sage 50, then you know the payroll is working correctly. If the employee wants something withheld they can either adjust their W4 or have you withhold a fixed amount from each check. You can put that amount in the "Addl Withholding" box on the Withholding Info tab.