Updated Checked by the Tax-Services.ca editorial team How we check
Canadian tax law is mostly two federal statutes, the Income Tax Act and the Excise Tax Act, plus a handful of smaller ones, and the Canada Revenue Agency runs them for the government. You don’t need to read either one to file a return. But you should know which one your problem falls under, because that decides the form, the deadline and the way you dispute a bill.
Which laws set your taxes?
Parliament writes the statutes. The CRA doesn’t make the law, it applies it. According to the CRA, it administers tax legislation such as the Income Tax Act and the Excise Tax Act for the federal government and for most provinces and territories.
| Law | What it covers for you |
|---|---|
| Income Tax Act | Tax on your pay, business income, gains, and the credits and deductions you claim |
| Excise Tax Act | GST/HST, charged on most sales |
| Taxation Act, 2007 (Ontario) | Ontario’s own rules for provincial tax credits and related items |
| Other acts on the CRA’s list | Among them the Excise Act, the Underused Housing Tax Act and the Global Minimum Tax Act |
The full text of the federal acts sits on the Department of Justice site, laws-lois.justice.gc.ca. It’s dense, and the section numbers matter more to lawyers than to you.
Do you ever need to read the act yourself?
Rarely. Most people never open it, and that’s fine. The CRA’s guides and forms turn the statute into steps you can follow. Reading the act itself starts to pay off when you’re disputing something unusual, and even then plenty of people ask a tax professional to read it with them.
If you do look, search for the section number the CRA quotes in its letter or guide. That gets you to the exact wording without wading through hundreds of pages.
Why does Ontario have a separate act?
Provinces set their own tax rates and credits. Ontario does it through the Taxation Act, 2007, and its text swaps the CRA for the Ontario Ministry of Finance wherever it borrows a federal provision. In practice you file one return, and the federal and Ontario pieces are worked out together.
You can see both layers at work in the income tax calculator, which splits the bill into federal and provincial tax. Quebec runs a separate return, so its law isn’t described here.
What can you do when you disagree with an assessment?
You have a formal route, and it has hard dates. For an individual under the Income Tax Act, the CRA says you get the later of two dates: one year after the filing deadline for that return, or 90 days from the date on your notice of assessment. Some notices, such as a loss determination or an RRSP or TFSA over-contribution assessment, get only the 90 days.
Say your 2025 return was due 30 April 2026 and the notice is dated 15 June 2026. Ninety days ends 13 September 2026, but one year after the filing deadline is 30 April 2027, so the later date is what counts. Corporations get exactly 90 days from their notice, and so do objections under the Excise Tax Act.
After you file, the CRA reviews it and either reassesses in your favour or sends a letter confirming its position. If you still disagree, the Tax Court of Canada must receive your notice of appeal within 90 days of the date the CRA sends its decision. It also lets you appeal if the CRA hasn’t decided within 90 days of your objection.
Put the dates in your calendar the day the notice arrives. An objection filed one day late can be refused, however good your case is.
What are regulations and CRA guidance?
Under the acts sit regulations, which the government can change without a new bill, and under those sits the CRA’s own guidance. Think of it as three layers: the act, the regulations that fill in the detail, and the guides and folios that explain how the CRA reads both. A guide can help you, but only the first two layers bind a court.
That’s why a CRA phone agent’s answer, however friendly, isn’t a ruling. If a lot of money rides on a position, a written reply from the CRA or advice from a tax professional is worth a few bucks more than a phone call.
How do the rules change what you actually pay?
The law sets thresholds, and thresholds move your bill. On $90,000 of Ontario income, the marginal tax rate calculator shows what your next dollar costs, which is a number the Income Tax Act creates through its brackets. Credits work the same way, so try the tax credits calculator for the federal amounts.
One warning on the marginal calculator. Around $200,000 in Ontario it reads very high because the Ontario Health Premium rises from $750 to $900 between $200,000 and $200,600 of taxable income, so don’t quote it as a rule.
What do people get wrong about tax law?
They treat a CRA web page as the law. The pages are the CRA’s plain-language reading of the act, and useful, but when a page and the statute disagree, the statute wins. They also assume an old rule still applies. The capital gains change is a good example: the proposed rise to two-thirds was cancelled by the Prime Minister’s release of 21 March 2025.
Don’t ignore a deadline because you think you’re right.
Business owners should also look at the self-employed tax calculator, since the rules for CPP and business income differ from those for employees.
Sources, and how we checked them
The list of acts the CRA administers and the objection and appeal deadlines come from Canada Revenue Agency pages, read in September 2026. The Ontario Taxation Act reference comes from the Ontario e-Laws text. Calculator figures use this site’s 2026 tax data. We aren’t a government service and we don’t speak for one.
Frequently asked questions
Who writes Canadian tax law?
Parliament passes the statutes. The CRA applies them, and it administers the Income Tax Act and the Excise Tax Act for the federal government and most provinces and territories.
Where can I read the Income Tax Act?
The Department of Justice publishes the consolidated federal acts at laws-lois.justice.gc.ca.
How long do I have to object to an assessment?
For an individual, the later of one year after the filing deadline and 90 days from the notice of assessment. Some notices allow only 90 days.
What if the CRA confirms its decision?
The Tax Court of Canada must receive your notice of appeal within 90 days of the date the CRA sends its decision.
Does Ontario have its own tax act?
Yes, the Taxation Act, 2007. You still file one return, and the federal and Ontario amounts are worked out together.
- How Canadian income tax works: brackets and credits
How federal and provincial Canadian income tax stack up, what marginal and average rates mean, and how credits and deductions change your bill