A big company may need advanced payroll software
Many employees would consider the wage department the most important in the company. This is for obvious reasons but an employer shouldn't become complacent when paying salaries and making deductions. Tax is a particularly tricky area and each employee will pay a different amount of tax depending on their circumstances. Some people have to pay student loans and this payment will need to be deducted every month. Some families get tax breaks and this also affects how much tax they pay compared to an employee who has no children. National insurance is also another deduction that needs to be considered and if a company is very large this can all get rather complicated.
Employing a system that can crunch all the numbers is vital and very advanced payroll software may need to be installed if a company has more than a hundred people working for it. Some people do take an interest in how much tax they're paying while others will just trust an employer to get the numbers right. It's sometimes a good idea to check what you're paying with a company that knows about tax deductions because this is an area which is constantly changing. As a country tries to balance its books it will keep changing how much tax people are expected to pay. This can be difficult to keep up with and not all media report these changes accurately. People work to earn money and they deserve as much of that money as they can get.