How Self-Employment Tax Works in Canada and the US

No One Withholds Your Tax Anymore

The biggest shift from employment to self-employment is invisible on payday and painful at filing: no one withholds tax from what you earn. An employee sees income tax and contributions deducted from every paycheque, so the year-end reconciliation is usually small. A self-employed person receives the full amount and is responsible for setting aside and remitting the tax themselves. That is why the single most important habit for any freelancer or contractor is to reserve a realistic percentage of every payment — commonly a quarter to a third, depending on income and province or state — in a separate account the moment it arrives.

On top of income tax, the self-employed carry a contribution burden that employees only half-see. In the United States, self-employment tax funds Social Security and Medicare at roughly 15.3% of net earnings, because you pay both the employer and employee halves (half of it is then deductible). In Canada, you pay both portions of the Canada Pension Plan on your net self-employment earnings, again roughly double an employee's share. These contributions are separate from and additional to income tax, and underestimating them is one of the most common reasons a first self-employed tax bill comes as a shock.

Instalments, Estimates, and the Deductions That Lower the Bill

Once self-employment income passes a modest threshold, paying once a year is no longer allowed. The IRS requires quarterly estimated tax payments, and the CRA requires instalments, each designed to approximate the withholding an employee would have had. Skipping them does not defer the tax — it adds instalment interest and penalties on top. Calculate what you are likely to owe, divide it across the required payment dates, and treat those dates as fixed obligations rather than optional prepayments.

The counterweight to all of this is deductions. Legitimate business expenses — supplies, software, professional fees, a reasonable home-office portion, and the business-use share of a vehicle — reduce the net income on which both tax and contributions are calculated. But every deduction has to be documented and honestly apportioned: home-office and vehicle claims in particular must reflect the genuine business-use fraction, calculated on a reasonable basis such as square footage or a mileage log. Overstated personal-use claims are a classic audit adjustment, and expenses you cannot prove are simply tax you overpay. Continuous record-keeping, with business and personal accounts kept separate, is what makes the deductions both maximal and defensible.

Are You Actually a Contractor?

A question that sits underneath all of this is whether you are truly self-employed at all. Both the CRA and the IRS look past the label on an invoice to the substance of the working relationship: how much control the payer has over how, when, and where you work; whether you can profit or lose; who supplies the tools; and how integrated you are into the payer's business. A worker treated as a contractor but functioning as an employee is misclassified, which changes who owes payroll tax and can affect access to benefits and legal protections. If your arrangement looks like disguised employment, it is worth clarifying before an assessment forces the issue.

Getting self-employment tax right, then, is mostly a matter of discipline rather than complexity: set money aside on every payment, pay your estimates or instalments on time, track and document deductions continuously, and confirm your classification and any sales-tax obligations early. Where income grows, revisit whether incorporating or registering for sales tax makes sense. This guide is educational only and is not tax or accounting advice; an accountant can tailor the set-aside rate, instalments, and deductions to your numbers.

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