Not completely definitive: http://wiki.c2.com/?WhyIsPayrollHard http://wiki.c2.com/?WhyIsPayrollHard And that's just scratching the surface of the types of pr

Not completely definitive: http://wiki.c2.com/?WhyIsPayrollHard http://wiki.c2.com/?WhyIsPayrollHard And that's just scratching the surface of the types of problems encountered. Statutory compliance makes payroll software complex. There can be many hundreds of rules defined by government and law (and combinations of these rules) that can affect how much money ends up in your pay packet. In addition to this the payroll software and the data held within needs to be continually kept up to date and compliant with any new rule, change of rule or removal of rules. That alone can mean many monthly updates just to keep in step with legislative changes.