Federal Withholding for Employee

[slacktide10]

As w2 season is here, I am a bit confused on the federal withholding. I have three employees (myself being one of them) who receive regular, weekly paychecks. We all are unmarried, with no dependents - yet the longer standing employee (who has therefore made more pay) has had less federal tax withheld than our newer employee. This employee has looked over their w-4 on their square app, and I have looked on square payroll at their w-4 and we both cannot see any mistake or mis-selected option which would cause the incorrect amount to be withheld. Is there something we are missing - or should I just advise them to just enter additional withholding to hopefully cover this next year?

[Donnie-M]

@slacktide10 Are the amounts paid weekly different?  Generally witholding is based on the gross amount of the paycheck and doesn't really look at the annual salary.  I know when I get a bonus check I am taxed in a whole different bracket than normally..etc.