sorry for bad english. Did anyone have ever making a payroll project? can you guys help me by giving me a concept in payroll system?thx

It depends on you on what will be going to be covered by your payroll program. In my case when we do the payroll include the leave of the employee and the login-logout of the employee in which it will affect on the "leaves" of the employee. Of course you will also the policies of a company how their payroll goes, and also about the deductions like taxes, SSS, etc.

The best approach for that is make an algo 'bout the processes to be done in payroll.