Advantages of filing taxes as business instead of personal

The income you earn from job will be taxed under the head 'Salaries'.

The other income will be taxed as Business/ professional income.

Even if you legally register a business, the income earned from that will be taxed under your PAN Like how it is taxed now. (unless you want to start a ltd company/ partnership). The expenses that you incurr for earning business Income shall be deducted from your Business Income. You should maintain proper record of the income as well as expenses.

It is better to consult a CA/ tax consultant in your area and ask him to prepare a income and expenditure account and Balance sheet.

You can show both income in a single ITR. Expenses incurred to earn in your business can be claimed as deduction under the head income from business/profession. Maintain proper records for accounting and income tax purpose.

agreed with above discussion 

but let us know the nature of business are you running to know which tax applicable on you