The #1 tax myth in Canada is that 'crossing into a higher bracket means you pay more on ALL your income.' It's completely wrong, and it causes people to turn down raises and overtime that would actually make them richer.

Here's how brackets really work. Imagine a staircase. Each step is a different tax rate. As your income climbs the staircase, each step applies only to the INCOME THAT CROSSED THAT STEP - not to the income below.

For 2025 federally: - First $57,375 → 15% - Next chunk (up to $114,750) → 20.5% - Next chunk (up to $177,882) → 26% - Next chunk (up to $253,414) → 29% - Everything above → 33%

If you earn $80,000, your federal tax is: (15% × $57,375) + (20.5% × $22,625) = $8,606 + $4,638 = $13,244 in federal tax, NOT 20.5% of $80,000.

Your MARGINAL rate is the rate on your NEXT dollar - the next dollar you earn (or don't). If you got a $5,000 raise, ALL of it lands in the 20.5% bracket. You'd pay 20.5% × $5,000 = $1,025 in extra federal tax. You'd STILL take home $3,975 more. Raises always make you richer.

MARGINAL TAX RATE = the rate on your next dollar. This is the number that matters for decisions: should I contribute to an RRSP? Should I take the overtime? Should I realize this capital gain? You're always deciding with marginal, not effective.

EFFECTIVE TAX RATE = total tax paid ÷ total income. This is what you actually pay AS A SHARE of your income, and it's always lower than your marginal rate because of the progressive brackets below the top one.

Example: Ontario, $80,000 income. - Marginal rate (combined fed + Ontario): ~29.7% - Effective rate (combined): ~22.5%

That 7-point gap is why: - 'I'm in the 30% bracket' doesn't mean '30% of my salary is gone'. - RRSP refunds are usually lower than you'd guess (they're calculated at marginal). - Canadians often overestimate how much of a raise goes to tax.

RULE: when making ANY financial decision that involves income, use the marginal rate. When comparing yourself to past years or other taxpayers, use the effective rate. Pick the right lens for the right question.

Your total Canadian income tax is the SUM of two separate calculations: federal tax and provincial tax. Both are calculated on the same taxable income, but each has its own brackets, rates, and credits.

Federal tax is the same no matter where you live. The 2025 brackets run from 15% on the first $57,375 up to 33% on income above $253,414.

Provincial tax varies dramatically by province. Alberta has a flat 10% on lower income with higher rates above $148k. Ontario starts at 5.05% and climbs to 13.16% with a surtax on top. Quebec runs its own completely separate system with rates from 14% to 25.75%.

Your COMBINED marginal rate is the federal rate plus the provincial rate that applies to your next dollar of income. For most middle-income Canadians, this lands between 29% and 43% depending on province. At the top brackets, the combined rate can exceed 53% in some provinces.

When people say 'I pay 30% tax,' they are usually quoting either their combined marginal rate or their effective rate - and confusing the two. The combined marginal rate tells you what the next dollar costs. The combined effective rate tells you what the average dollar costs.

Every Canadian individual files a T1 General income tax return, covering income earned from January 1 to December 31 of the calendar year. The return is due April 30 for employed individuals and June 15 for self-employed (though any balance owing is still due April 30).

The T1 is divided into sections: total income (employment, business, investment, rental, other), net income (after deductions like RRSP contributions, union dues, childcare), taxable income (after additional deductions), and federal/provincial tax payable (after credits).

You do not need to fill in the T1 by hand. Tax software does it for you. But understanding the flow helps you make better decisions: deductions reduce your net income (saving at your marginal rate), while credits reduce your tax payable (saving at the credit rate, usually 15% federally).

THE CALENDAR YEAR RULE: all income, deductions, and credits must fall within the Jan 1 - Dec 31 window to count for that year's return. The only major exception is the RRSP, which has a 60-day grace period (contributions made in the first 60 days of the new year can count toward the prior year). Everything else - donations, medical expenses, capital gains - must be realized by December 31.

Quebec residents file a SECOND return (the TP-1) with Revenu Quebec. Every other province piggybacks on the federal T1.