How do Canadian tax authorities generally approach auditing someone with significant gambling activity?

The default rule — and why it's not the end of the story

Lottery and certain other winnings are non-taxable in Canada — but if the CRA concludes that a taxpayer is in the business of gambling, the proceeds and losses become subject to income tax. That distinction is the fulcrum everything else turns on, and it's where audits focused on heavy gambling activity tend to spend most of their time.

The CRA's own technical guidance — Income Tax Folio S3-F9-C1 — notes that traditional tests for a business include a profit-making purpose, but gambling is always undertaken in pursuit of profit. Courts have held that wanting to win money, "shared by all who gamble," does not by itself lead to the conclusion that all frequent gamblers are carrying on a business. So volume alone doesn't flip the switch. Even regular, frequent, and systematic gambling is something that by its nature is not generally regarded as a commercial activity except under very exceptional circumstances, per the Tax Court's reasoning in Leblanc v. The Queen. The exceptional cases, noted in that same decision, relate to taxpayers who applied inside information, knowledge, and skill to their activities.

How a CRA auditor actually examines the picture

When an auditor's attention is drawn to significant gambling activity — whether through a lifestyle review, bank deposit analysis, or a taxpayer's own explanation — the approach is methodical. Non-taxable lottery and other winnings may arise when an auditor is trying to identify the source of funds supporting a taxpayer's accumulation of assets, lifestyle, and deposits to personal bank accounts. If the taxpayer states that gambling winnings are the source of those funds, the auditor will request documentation covering all winnings and losses.

The broader audit tool here is the net worth method. The net worth method is the most common indirect verification technique used by the CRA. The auditor considers changes in assets and liabilities, personal spending, and other relevant information — including non-taxable sources such as lottery winnings — and then compares the resulting income figure to what was reported on the tax return. This method goes beyond books and records and involves a comprehensive review of the taxpayer's lifestyle using personal financial records and other verifiable information, such as motor vehicle registration and land title information.

A practical wrinkle the CRA's own audit manual flags: a taxpayer may often recall wins but need to be prompted to recall losses. That asymmetry matters — if you're claiming gambling as the explanation for unexplained deposits, you need to account for both sides of the ledger. If there is genuine doubt about the receipt of lottery or other winnings, the benefit of the doubt must be decided in the taxpayer's favour.

For online gambling specifically, regulated Ontario operators — identifiable by the iGaming Ontario and BetGuard logos on their sites — maintain account transaction histories. That paper trail can actually work in a player's favour: it's contemporaneous, operator-generated documentation of both deposits and withdrawals, which is far more credible than reconstructed records.

What this means practically for Ottawa players

For the vast majority of recreational players, gambling winnings from licensed Ontario sites remain non-taxable. The risk of a taxability finding rises only when the activity starts to look like a systematic, skill-driven commercial operation. Even then, the CRA's own windfall factors include whether the taxpayer made no organized effort to receive the payment, had no customary expectation of it, and whether it came from a source that is not a customary source of income. Casual and even regular recreational play generally satisfies several of those criteria.

If you do get a CRA inquiry touching on gambling activity, the practical advice is straightforward: download your transaction history from your Ontario-licensed operator, keep it organized by year, and get a tax professional involved early. The question of whether gambling rises to the level of a business is genuinely fact-specific and worth getting right — the CRA's guidance is clear that it's not a mechanical test. If gambling ever becomes something other than entertainment for you, ConnexOntario (1-866-531-2600) is there. And always confirm any operator you use is registered with iGaming Ontario before you play.