I just got hooked up with the Forum and happen to know a couple of relevant things on this topic. Re computing OT with a semi-monthly payroll, we have had that schedule for years and ADP cannot do the necessary adjustments, which we must do by hand. In my opinion the issues with a bi-weekly payroll are nothing compared to the hassles of a semi-monthly schedule. The problem of OT needing to be based on calendar weeks and pay periods almost never falling on calendar weeks requires a lot of unnecessary adjustments, and even if you get it right it is practically impossible to explain to employees. And, depending on when you actually cut checks, you may have to use estimated hours and adjust for corrections in each following pay cycle. And, if you pay any bonuses (and many types of commissions) you also have to find a way to work those amounts into the OT calculation as "regular pay".

I'll take the 10-year 27th payday problem over the weekly/monthly hassles with a semi-monthly payroll!