The big idea: not all your income is taxed the same way
Canada uses a progressive tax system. Your income is sliced into brackets, and each slice is taxed at its own rate, federally and provincially.
Two key concepts:
- Marginal tax rate: the rate you pay on your next dollar of taxable income (the top “slice”).
- Average (or effective) tax rate: your total tax divided by your total income—usually much lower than your marginal rate.
In Ontario for 2025, combined federal–provincial marginal rates on salary/interest income range roughly from about 20% at lower incomes up to about 53.53% at the very top. That means some of your dollars may be taxed at 20%, some at 30%, some at 40%+, all within the same year.
If you don’t understand which slice you’re in, you can’t plan properly.
A simple example (without the math headache)
Let’s say you live in Ontario and have 100,000 of employment income in 2025.
- The first portion of your income is taxed at the lowest combined federal–provincial rates.
- Each bracket above that gets a slightly higher rate.
- Only the income in the top bracket you reach is taxed at your marginal rate.
So if your marginal tax rate is around 43%, that does not mean 43% of the entire 100,000 is going to tax. It means every additional dollar above the threshold for that bracket is taxed at roughly 43%.
This distinction matters as it helps you determine:
- When you earn an extra 10,000 bonus,
- When you decide whether to contribute to an RRSP,
- When you choose which account to withdraw from in retirement,
- When you decide whether to trigger a capital gain this year or next.
Why your marginal tax rate is a power tool, not trivia
Once you know your marginal tax rate, you can start making intentional moves instead of guesses.
Here’s what it helps with:
- RRSP contributions
A 5,000 RRSP contribution saves you tax at your marginal rate. If your marginal rate is 43%, that contribution could save you about 2,150 in tax this year. - Choosing between RRSP and TFSA
If your current marginal rate is high and your future retirement rate is likely lower, RRSP contributions are often more attractive. If the opposite is true, TFSA might be better. - Timing income and deductions
You might push extra income (bonuses, dividends, capital gains) into a year when your marginal rate will be lower, and pull deductions (RRSP, business expenses) into a year when your marginal rate is higher. - Structuring business and investment income
Salary, dividends, capital gains and corporate income are all taxed differently. Knowing your marginal rate lets you design how much to take, when, and from where.
In short: knowing your marginal tax rate turns tax from a black box into a planning tool.
How to find your marginal tax rate
You don’t need to be a tax pro to get a good estimate.
- Grab last year’s Notice of Assessment or return.
Look at your taxable income and total tax paid. - Use a 2025 tax calculator or marginal tax table.
Several tools publish combined federal–provincial marginal tax rate tables each year for Ontario and other provinces.- Match your taxable income to the bracket.
- The table will show your marginal rate for ordinary income in that band.
- Identify your “top slice”.
That marginal rate is the cost of each extra dollar you earn (or the value of each dollar of deduction you can create) this year.
Doing this step to determine your marginal tax rate is so important and more so if you’re a business owner, if you have multiple income sources, or if you see large swings in your income from year to year.
How to actually use this in your life
Once you know your marginal tax rate, ask:
- Where can I move income out of high-tax slices?
- RRSP or pension contributions
- Income splitting with family where allowed
- Holding certain investments in a corporation or different account type
- Where can I move income into lower-tax slices?
- Spreading a large bonus or dividend over two years
- Timing the sale of an investment or property
- Planning retirement withdrawals to avoid jumping brackets
- Which dollars should I protect first?
- High‑rate years = maximize RRSP and other deductions
- Lower‑rate years = focus on TFSA, paying off non‑deductible debt, and strategic capital gains harvesting
Every strategic dollar you move can save 30–50+ cents in tax, depending on your bracket. Over a decade or two, those savings compound into real wealth.
This tax season: don’t just file, optimize
Most people will file their 2025 return, glance at the refund or balance owing, sigh in relief or frustration—and move on.
If you’re serious about building tax‑efficient wealth, you can’t afford that approach.
This year, I’d encourage you to:
- Find your current marginal tax rate.
- List the biggest levers you have (RRSP, TFSA, corporate structure, investment accounts, real estate, business income).
- Build a simple one‑page plan for how you’ll use your marginal rate to your advantage over the next 12 months.
This is exactly the kind of thinking I lay out in my book, Tax-Efficient Wealth, where I show how marginal tax rates, types of income, and the right tools fit into a bigger blueprint for building wealth in Canada.
Your next step: learn the blueprint, then apply it
If you:
- Don’t know your marginal tax rate,
- Have income in the 50,000–300,000+ range, or
- Own a corporation, rental, or investments,
…then understanding and using your marginal tax rate is no longer optional. It’s the difference between just “earning a good income” and actually keeping more of it.
I wrote Tax-Efficient Wealth to give Canadians a clear, practical roadmap for exactly this – how to use our tax system, including marginal rates, to accelerate wealth instead of eroding it.
Order your copy of Tax-Efficient Wealth here:
https://kengreen.ca/book/
Then, as you file this year’s return, let’s make sure you’re not just paying tax—you’re using the tax rules to build the future you actually want.
