Hi Suin - What is your accountant's advise on the income query/question you have? If you are self-employed and claim expenses, then subtract those expenses from your gross income to get Net Income. Therefore, for self-employed people, Net income is to be used for LICO eligibility. In case of a salaried employee, gross income is net income because that salaried employee cannot claim any expenses.
You can get Gross/total income, from Line 150 of Notice of Assessement (that you get after filing taxes) for a particular tax year. And line 236 is your Net Income after deductions. If you are confused with respect to income, I would highly recommend you to take advise from an accountant.