When calculating your debt ratio, you should include your employment income and pension income. You can include self-employment income, investment income, and other variable income if you can document that you’ve earned it consistently over two years. Net rental income can also be added, provided you’re not applying for a mortgage for a property generating rental revenue. Should the mortgage be for an investment rental property, you can only apply 50% of your gross annual rental income. If you’ll be occupying the rental property alongside your tenants, you can use 100% of your yearly gross income in your ratio.