Determine taxable income by deducting any pre-tax contributions to benefits Your taxable income can be calculated by subtracting deductions (you are eligible to deduct) from your gross income. Your gross income is collectively the wages, profits, interest payments, rental income, and any other form of earning during the year. Once you have calculated your gross income by summing up all your earnings, you have to deduct amounts that you are allowed to deduct. Find out if you are eligible for Nunavut taxes deductions or federal tax deductions.