When you have a small office and only a few staff members, payroll is still complicated yet not as hectic as that of a large corporation. Being a complicated affair, payroll takes up time and effort to get right and maintain. When in a small office it is often found that office staff multitasks across task spectrums and fulfill more than one position at a time.
For instance, your office administrator may also be handling data capturing, the accounting and your payroll. This is a lot for one person to handle and payroll takes time away from the other tasks that need tending to.
This way it takes longer to deal with data capturing and accounting duties. With payroll outsourcing your staff will save time and be able to be more productive in other areas of their jobs.