What Triggers a CRA Audit? Common Red Flags for Canadian Taxpayers

Receiving a letter from the Canada Revenue Agency (CRA) asking to review your tax return can be stressful — even if you've done nothing wrong. Understanding what triggers a CRA audit is the first step to protecting yourself and responding calmly if you are selected.

CRA audits are not random accusations of fraud. Most are routine reviews driven by data matching, industry norms, or specific reporting patterns that flag an account for a closer look. This article explains the most common triggers, what the CRA is actually looking for, and what Ontario taxpayers can do when they receive an audit letter.

How CRA Selects Returns for Audit

The CRA uses several methods to decide which returns to examine.

Computer scoring and risk assessment

Every tax return you file is processed through the CRA's automated systems. The system assigns a risk score based on how your numbers compare to similar taxpayers — people in your industry, income bracket, and region. If your deductions look unusually high relative to your income, or your reported income looks unusually low for your occupation, your return may be flagged for human review.

Industry-specific comparisons

CRA analysts have access to industry benchmarks. If you run a restaurant and report a gross margin much lower than the industry average, that gap is a signal. The same applies to consultants, contractors, real estate agents, and other self-employed professionals in Ontario.

Information matching

The CRA receives income information from employers, banks, investment platforms, and other third parties. If those slips don't match what you reported, the system catches it. T4s, T5s, T3s, and RRSP contribution receipts are all cross-referenced automatically.

Referrals and tips

The CRA operates a leads program. Tips from former business partners, disgruntled employees, or even competitors can initiate a review — especially in cash-heavy industries.

Common Audit Triggers

The following patterns frequently lead to CRA scrutiny. They don't mean you've done anything wrong, but they do mean your return may get a second look.

Large or unusual deductions

• Home office expenses claimed by someone without a clear business need
• Vehicle expenses at or near 100% business use
• Meals and entertainment deductions that seem high for the type of business
• Significant charitable donation claims, especially without proper receipts

Self-employment and business income

Self-employed individuals and incorporated business owners face higher audit rates than T4 employees. The CRA knows that cash income is harder to verify, so it looks more closely at:

• Gross revenue that fluctuates significantly year over year
• Business losses claimed for multiple consecutive years (raises the question of whether a genuine profit motive exists)
• Cash-based businesses in sectors like construction, food, or personal services

Real estate transactions

Ontario's real estate market gets significant CRA attention. Audit triggers include:

• Frequent property purchases and sales that look more like a business than capital investment
• Reporting the sale of a principal residence but not meeting the eligibility criteria for the exemption
• Rental income not reported at all, or expenses claimed against rental income that look inflated

Foreign income and foreign assets

If you have bank accounts, investments, or property outside Canada above the reporting threshold (as of writing — verify the current amount with CRA), you must file reporting forms. Failing to report foreign income or assets is a significant audit trigger and can result in substantial penalties.

RRSP and TFSA issues

Over-contributing to a TFSA or making prohibited investments inside a registered account can draw CRA attention. The CRA monitors registered account activity and will reassess if it spots unusual transactions.

Types of CRA Audits

Not every audit is the same. Knowing the type helps you understand the scope.

Desk audit (correspondence audit): The most common type. CRA sends a letter asking you to send specific documents — receipts, bank statements, or invoices — by mail or online. You don't need to visit a CRA office.

Field audit: A CRA auditor visits your home or business to review your records in person. More common for businesses with substantial revenues.

Net worth audit: Used when CRA believes your reported income is too low to support your lifestyle. The auditor estimates your income by comparing your net worth at the start and end of the year, factoring in spending. This can be invasive and is most common in cash-heavy industries.

What to Do If You Receive an Audit Letter

1. Read carefully. The letter tells you exactly what CRA wants — specific years, specific line items. Don't assume the worst.
2. Gather records. Locate the receipts, bank statements, contracts, or invoices the CRA is asking about.
3. Meet deadlines. CRA sets response deadlines. Missing them can result in arbitrary reassessments.
4. Get professional help. If the audit involves significant amounts, multiple years, or complex business issues, consult a tax lawyer or accountant before you respond. What you say to the CRA during an audit can be used against you in a later dispute.
5. Don't volunteer extra information. Answer what's asked. You don't need to send documents beyond what the CRA has specifically requested.

Frequently asked questions