Can I use a business loss from my self-employment to reduce my other income in Ontario?

Yes. One of the significant advantages of operating as a sole proprietor is that a business loss can generally be applied against other income in the same year — including employment income, investment income, or a spouse's income in some limited circumstances. The loss appears on your T1 and reduces your overall net income, which reduces both federal and Ontario provincial taxes.

If the business loss is larger than your other income in the year, you can carry the unused loss back up to three tax years or forward up to 20 years to apply against income in those years. These are called Non-Capital Loss carryovers under the federal Income Tax Act.

There is an important limitation: if the CRA determines that your activity is a "hobby" rather than a genuine business — particularly if losses recur year after year with no reasonable expectation of profit — it may deny the losses entirely. The CRA looks at factors like your commercial intent, history of profit, training and expertise, and the time and resources committed to the activity. Demonstrating genuine business intent and a credible path to profitability is important for recurring loss claims.