I have limited people that I do payroll with seasonally so I just have a sticky note next to my monitor with the SS & Med rates and use the built in calculator feature of QB to figure out those numbers.  For Federal withholding I just take a fixed percentage since my employees are part timers and want a larger amount taken out each pay period.  Same goes for ND, I have one guy who wants ND tax withheld otherwise I do not do the state amount since I am not required to withhold state money for agricultural employees.  I also use the same program to do the books for my church and the employees there are getting a set monthly amount so it is just a once a year event for figuring amounts.