Every year, thousands of Canadian businesses and high-net-worth individuals file income tax returns with errors that cost them money, invite CRA scrutiny, or both. Some of these mistakes are obvious in hindsight. Others are genuinely nuanced — the product of rules that are poorly understood, frequently misapplied, and occasionally updated without much fanfare.
This post is not for the person filing a T1 with employment income and a few RRSP contributions. It’s for the owner-manager who draws a mix of salary and dividends from a corporation, the investor managing a portfolio of capital properties, and the professional whose tax return has real complexity — and real consequences if it’s done wrong.
Here are five of the most consequential errors we see in Canadian income tax returns, what the CRA looks for, and what to do instead.
Error #1: Mishandling Shareholder Loans and Benefits Under Sections 15(1) and 15(2)
This is, without question, the single most dangerous area for Canadian owner-managers — and the one most likely to result in a reassessment that creates genuine financial pain.
The problem: treating your corporation like a personal bank account
When a corporation pays a shareholder’s personal expenses, sells corporate property to a shareholder for less than fair market value, or advances funds to a shareholder without a proper repayment structure, the Income Tax Act treats those amounts as taxable income to the shareholder — even if the shareholder genuinely intended to repay them or thought the arrangement was legitimate.
There are two distinct mechanisms to understand:
Section 15(1) — Shareholder Benefits. Under subsection 15(1) of the Income Tax Act, any benefit conferred by a corporation on a shareholder must be included in that shareholder’s income at fair market value. The CRA’s Income Tax Audit Manual confirms that this applies to personal expenses paid by the corporation, corporate property used personally without appropriate rent or reimbursement, and assets sold to shareholders at below-market prices. The difference between what the shareholder paid and the fair market value of the benefit is taxable income.
What makes this rule particularly punishing is the double-taxation effect. The corporation pays the expense from after-tax dollars (and is denied a deduction), while the shareholder must include the same amount in their personal income. It is a worse outcome than simply paying a bonus or dividend in the first place.
Section 15(2) — Shareholder Loans. Under subsection 15(2), if a corporation advances money to a shareholder and that loan is not repaid before the end of the corporation’s fiscal year following the year the loan was made, the entire loan amount is added to the shareholder’s personal income in the year it was originally advanced. There is no corresponding deduction for the corporation.
The repayment deadline under section 15(2) is not intuitive. If your corporation has a December 31 year-end and you take a $100,000 advance on March 15, 2025, you have until December 31, 2026 — the end of the next fiscal year — to repay it before it becomes taxable. Miss that date, and you owe tax on $100,000 of income — at a marginal rate of up to 53.53% in Ontario — even if the money is long gone.
The fix
Every shareholder transaction needs to be intentional and documented. If your corporation is paying for something on your behalf, it must either be a properly reported and taxable benefit, or it must be charged back to you at fair market value. Advances must be tracked in a shareholder loan account, supported by a written loan agreement with a repayment schedule and interest charged at or above the CRA’s prescribed rate. When in doubt, declare a bonus or dividend. These are less elegant than an advance, but they are unambiguously correct.
Error #2: Over-Claiming Business Expense Deductions — Particularly Meals, Entertainment, and Vehicles
For small business owners and high-net-worth individuals with self-employment income, the temptation to maximize expense deductions is understandable. The rules, however, are unforgiving on specific categories, and the CRA’s audit algorithms have become sophisticated at detecting patterns that fall outside industry norms.
Meals and entertainment: the 50% rule is not optional
The CRA’s rules on meals and entertainment deductions are set out clearly in the business expenses guide: the maximum deductible amount for food, beverages, and entertainment is 50% of the lesser of the amount actually paid or a reasonable amount. This applies to client dinners, business lunches, tickets to sporting events, and cover charges at hospitality suites. There are limited exceptions — company-wide staff events (up to six per year), fundraising events for registered charities, and remote work-site meals — but these exceptions are narrow and require specific conditions to be met.
We regularly see businesses claiming 100% of meals and entertainment as deductions, or including amounts that are clearly personal in nature. The CRA can and does request detailed substantiation: who attended, what was the business purpose, and are there contemporaneous receipts to support the claim? Without this, the deduction will be denied.
Automobile expenses: no log, no deduction
If you use a vehicle for both personal and business purposes, you can only deduct the business-use portion of expenses such as fuel, insurance, maintenance, and lease payments. The CRA’s own guidance states that you must maintain a logbook to establish total kilometres driven and kilometres driven for business purposes. Without a logbook, an auditor has no basis to accept the claimed business-use percentage.
For incorporated businesses that provide vehicles to shareholder-employees, the rules become more complex. If the vehicle is available for personal use, a standby charge and an operating cost benefit must be calculated and reported on the shareholder’s T4 — and the relevant GST/HST adjustments must also be made. Failing to report these benefits is a common source of reassessment.
Capital expenditures vs. current expenses: a persistent confusion
Many business owners claim capital expenditures — equipment, leasehold improvements, major renovations — as fully deductible current expenses in the year incurred, when in fact these must be capitalized and depreciated over time through Capital Cost Allowance (CCA) under the applicable CCA class. The distinction between a deductible repair (restoring an asset to its original state) and a capital improvement (enhancing or extending the asset’s useful life) is not always obvious. Getting it wrong in either direction can create problems.
The fix
Maintain a mileage logbook — either paper or digital — throughout the year. Keep receipts for every meal and entertainment expense, recording the names of attendees and the specific business purpose at the time of the expense. Have your accountant review your expense categories before filing to ensure that capital items are being treated correctly.
Error #3: Incorrect — or Missing — Capital Gains Reporting
Capital gains are one of the most heavily scrutinized areas of Canadian income tax, and errors here tend to be material. For business owners with investment portfolios, real estate holdings, or interests in private corporations, capital gains reporting requires careful attention every year.
Failing to report all dispositions
The CRA requires that every disposition of capital property be reported on Schedule 3 of the T1 return, even if no tax is owing. This includes dispositions that result in a capital loss, deemed dispositions (such as when property changes use between personal and income-producing), and transfers of capital property to a related party. Incomplete reporting is one of the most common triggers for a CRA review.
Errors in adjusted cost base (ACB) calculation
The ACB of a capital property is not always what you paid for it. For publicly traded securities bought and sold over time, the ACB must be recalculated each time you acquire more units of the same property using the averaging rules set out by the CRA. For real estate, the ACB may include closing costs, improvements made over the years, and, in some cases, adjustments related to prior principal residence designations. Systematically underestimating the ACB results in an overstated capital gain; overestimating it is equally problematic and may attract CRA scrutiny on reassessment.
The principal residence exemption: don’t assume it’s automatic
Since 2016, the CRA has required taxpayers to report the sale of a principal residence on Schedule 3 and to file Form T2091(IND) even if the property was their principal residence for every year they owned it. Failing to make this designation means failing to claim the exemption — and the CRA will not apply it automatically. The agency has confirmed it will accept late designations in certain circumstances, but a penalty may apply.
For individuals who rent out part of their home, who have converted a property from principal residence to income property (or vice versa), or who have owned properties in both Canada and abroad, the principal residence rules require careful analysis.
The 2024 capital gains inclusion rate question
The proposed increase to the capital gains inclusion rate from one-half to two-thirds — originally set to apply to dispositions on or after June 25, 2024 — introduced significant complexity for 2024 returns. Although the proposed increase was subsequently deferred to January 1, 2026, the CRA maintained a two-period reporting structure on 2024 Schedule 3. Taxpayers with 2024 dispositions needed to bifurcate their gains into a pre-June 25 period and a post-June 25 period — a step that many overlooked. With the inclusion rate change now deferred to 2026, this remains an active area for planning.
The fix
Keep meticulous records of every capital property you own: the original purchase price, all closing costs, all capital improvements, and any prior elections or designations made. Report every disposition on Schedule 3, regardless of whether you believe tax is owing. If you’ve sold a principal residence and aren’t sure whether the exemption has been properly claimed, have a CPA review your prior years’ returns.
Error #4: Misclassifying Workers as Independent Contractors
Worker misclassification is an issue that affects both the T1 and T2 returns, the GST/HST account, and the payroll remittance account — sometimes all at once. It is one of the few errors that can result in simultaneous reassessments across multiple tax programs.
The distinction matters enormously
The CRA does not allow businesses to simply label a worker a contractor to avoid payroll obligations. Whether a worker is an employee or a self-employed contractor depends on the actual nature of the relationship, assessed against factors including control, ownership of tools, risk of profit and loss, and integration into the business. The CRA’s guidance on this question is set out in RC4110, Employee or Self-Employed?
When the CRA determines that a worker classified as a contractor is actually an employee, the consequences cascade:
- The employer is assessed for the employee’s share of CPP and EI, plus the full employer’s share, going back potentially several years.
- Any GST/HST input tax credits claimed on payments to the misclassified worker are disallowed, because employees do not charge GST/HST.
- The corporation may be denied the business expense deduction on the payments.
- Penalties and interest apply to all unpaid remittances.
This is particularly acute for professionals — law firms, engineering firms, accounting practices — who routinely engage associates or project-based workers on a contractor basis. It is also a significant risk for businesses that have the same “contractor” working exclusively for them, using their tools, on their premises, on an ongoing and integrated basis.
The fix
If you have workers whose status could reasonably be questioned, request a ruling from the CRA using Form CPT1. A ruling provides certainty in advance and protects you if the CRA later takes a different view. Structure contractor arrangements to reflect true independence: separate business registration, their own tools and workspace, multiple clients, and the ability to subcontract.
Error #5: Missing, Incomplete, or Incorrect Information Returns
The final error category is less about aggressive tax planning and more about compliance gaps that result in penalties — often significant ones — with no corresponding tax benefit whatsoever.
The T1135 — Foreign Income Verification
If you held specified foreign property with a total cost of $100,000 CAD or more at any point during the tax year, you were required to file Form T1135, Foreign Income Verification Statement, by your filing due date. Specified foreign property includes foreign bank accounts, foreign investment accounts, shares of foreign corporations, foreign real estate not used in a business, and interests in foreign trusts, among others.
The penalties for non-compliance with T1135 are severe. A late or unfiled T1135 attracts a penalty of $25 per day, up to a maximum of $2,500, for simple late filing. Where the failure is found to be due to gross negligence, the penalty increases to 5% of the maximum cost of the foreign property in the year — up to $500,000 — in addition to any tax owing on unreported income. High-net-worth Canadians with international investment holdings must treat T1135 filing as a non-negotiable annual obligation.
The T106 — Non-Arm’s Length Transactions with Non-Residents
Corporations that have transactions with non-resident related parties must file Form T106, Information Return of Non-Arm’s Length Transactions with Non-Residents, if total transactions exceed $1 million CAD in the year. Transfer pricing is one of the CRA’s highest-priority compliance areas, and Form T106 is its early warning system.
Deadlines and late-filing penalties
For individual filers (T1), the standard filing deadline is April 30. Self-employed individuals and their spouses have until June 15, but any balance owing is still due by April 30 — interest begins accruing on May 1 on any unpaid balance. For corporations (T2), the return must be filed within six months of the fiscal year-end, but the balance of tax owing is due two months after year-end (three months for CCPCs eligible for the small business deduction).
Late filing carries a penalty of 5% of the balance owing, plus 1% per complete month the return is late, up to 12 months — and the penalty doubles for a second late-filing offence within three years. For high-net-worth individuals with significant tax payable, the dollar cost of late filing can be substantial.
The fix
Build a compliance calendar. Know your filing deadlines, your payment deadlines, and which information returns apply to your situation at the start of each fiscal year, not at the end. If your financial affairs include foreign assets, related-party transactions, or a corporate structure, engage a CPA who works proactively — not one who simply processes your return in the spring.
The Common Thread: Proactive Professional Guidance
Looking across all five of these error categories, the common thread is clear: the errors that hurt the most are the ones that accumulate quietly, year after year, until a reassessment arrives. Many of the situations described above — shareholder advances that grow without documentation, capital property records that aren’t maintained, information returns that were never filed — are far more difficult and expensive to resolve retroactively than they would have been to handle correctly from the start.
At Martin-Weaver Chartered Professional Accountants (MWCPA), our small business accounting and tax services are designed specifically for owner-managers, high-net-worth individuals, and businesses with complex, non-routine tax situations. We provide year-round proactive advice — not just return preparation — so that you identify and address these issues before the CRA does.
If your current approach to tax filing feels reactive, or if any of the scenarios described in this post sound uncomfortably familiar, we’d welcome the opportunity to talk. Book a free initial consultation and let’s take a clear-eyed look at where you stand.
The information in this post is provided for general educational purposes and reflects the state of Canadian income tax law as of the date of publication. It does not constitute tax or legal advice. Tax rules change frequently, and individual circumstances vary. Please consult a qualified CPA or tax advisor before acting on any information contained here.
Martin-Weaver Chartered Professional Accountants provides accounting and tax services for Canadian small businesses, owner-managers, and non-residents with Canadian tax obligations. Contact us at info@mwcpa.ca or +1 (289) 301-0074.
