1. Add up your income. To create a monthly budget, you should first determine how much income you have by listing your monthly income including salaries or wages, interest, pension and any other sources, such as a spouse’s income. If you earn a salary, be sure to list your take-home pay rather than your gross pay—pay before any deductions, like taxes, come out. And if taxes aren’t automatically deducted, remember to include them as another expense.