Back Office SAGE PAYE program required

This is for a DeskTop Back Office program. Need a program to work out my income tax and the tax and NI which I deduct from my staff. Similar to SAGE but not as complicated to use. I will just input hours of each employee and provide you with formula for calculating tax Employees are allowed to work certain hours before tax is deductable This varies depending on marital status Also needs to carry details of all invoices we pay This will need to be split into many different categories Reports will be required for any date range I choose There will be many tweaks required so I need somebody who is prepared to work with me for long time