Cross-Border Tax for Canadians: What to Know Before You Do Business in the U.S.
Business — and life — doesn’t stop at the border. Plenty of Burlington and GTA business owners sell into the United States, expand south, or hold U.S. investments. Plenty of Canadians are also U.S. citizens or green card holders. In every one of those situations, you’re dealing with two tax systems at once — and they don’t always agree.
The good news is that the Canada–U.S. tax treaty exists precisely to stop you from being taxed twice on the same income. The catch is that the relief isn’t automatic: you have to file the right forms, in the right country, on time. Here’s a plain-English overview of where cross-border tax shows up and what to watch for.
The two most common cross-border situations
Cross-border tax usually arrives in one of two forms:
You’re a Canadian earning income or doing business in the U.S. (selling to U.S. customers, expanding operations, or holding U.S. property or investments).
You’re a U.S. citizen or green card holder living in Canada — which means the IRS still expects a return from you every year, no matter how long you’ve been in Canada.
The rules are different for each, so let’s take them in turn.
If you’re a Canadian doing business in the U.S.
Selling into the U.S. doesn’t automatically make you taxable there — but crossing certain lines does.
The treaty is your friend, but you have to claim it. Under the Canada–U.S. tax treaty, a Canadian business is generally only taxable on U.S. business profits if it has a “permanent establishment” (a fixed place of business, like an office, warehouse, or dependent agent) in the U.S. Even when the treaty protects you, you often still need to file a U.S. return to claim that protection — silence isn’t a strategy.
Watch the U.S. LLC trap. A U.S. LLC is popular and flexible for Americans, but for Canadians it can create a costly mismatch: the U.S. and Canada treat the LLC differently, which can lead to double taxation that the treaty won’t fully fix. Choosing the right structure before you expand is far cheaper than untangling it later.
State taxes are their own world. Beyond federal tax, individual states have their own rules and “nexus” thresholds — and selling online into many states can trigger filing obligations you didn’t expect.
Forms like the W-8BEN matter. Giving U.S. payers the correct withholding forms helps ensure you aren’t over-withheld on U.S.-source payments.
If you’re a U.S. citizen or green card holder living in Canada
This is the one that surprises people most: the U.S. taxes based on citizenship, not just residency. If you’re a U.S. person, you must file a U.S. tax return (Form 1040) every year reporting your worldwide income — even if you’ve lived in Canada for decades and owe nothing.
You generally won’t be taxed twice, thanks to two key mechanisms:
The Foreign Earned Income Exclusion (Form 2555), and/or
The Foreign Tax Credit (Form 1116), which credits the Canadian tax you’ve already paid against your U.S. liability.
But filing the 1040 is only half the job. U.S. persons in Canada also have information-reporting obligations with steep penalties for missing them:
FBAR (FinCEN Form 114): if your foreign (i.e., Canadian) financial accounts add up to more than $10,000 USD combined at any point in the year, you must report them. That’s an aggregate threshold across all accounts — not per account.
FATCA (Form 8938): a separate IRS form for specified foreign financial assets above certain thresholds.
Be careful with TFSAs and RESPs. These are wonderful tax shelters in Canada — but the IRS often doesn’t recognize them as tax-free and may treat them as foreign trusts, creating extra U.S. reporting. For many U.S. persons in Canada, these accounts cause more trouble than they’re worth.
Snowbirds: the substantial presence test
Spend a lot of the winter in Florida or Arizona? You could be considered a U.S. resident for tax purposes even without a green card. The IRS uses the substantial presence test: broadly, you meet it if you’re in the U.S. at least 31 days in the current year and 183 days over a three-year weighted period (all of this year’s days, one-third of last year’s, and one-sixth of the year before).
If your day count is getting close, the Closer Connection Exception (Form 8840) lets eligible snowbirds document that their real home and ties are in Canada — keeping them out of the U.S. tax net. It only works if you file it on time.
Don’t forget the Canadian side: Form T1135
Cross-border reporting runs both ways. If you’re a Canadian resident who owns specified foreign property with a total cost over $100,000 CAD at any time during the year — U.S. rental real estate, U.S. brokerage accounts, and similar — you must file the CRA’s Form T1135 (Foreign Income Verification Statement) with your return. Penalties for missing it start at $25 per day (up to $2,500) and climb from there, so it’s not one to overlook.
The cost of getting it wrong
Cross-border mistakes are expensive in two directions: double taxation (paying full tax in both countries because relief wasn’t claimed properly) and information-return penalties (often charged even when no tax was owed). The encouraging news is that almost all of it is avoidable with planning and timely, correct filings.
Cross-border tax done right — Shandal CPA
This is exactly where having an accountant on both sides of the border pays off. Manu Shandal holds both his U.S. and Canadian CPA designations, so we help Burlington, GTA, and Ontario clients — Canadians expanding into the U.S., U.S. citizens living in Canada, and snowbirds alike — stay compliant in both countries while paying only what they actually owe.
If your business or your personal finances cross the Canada–U.S. border, let’s make sure you’re structured and filing correctly. Call (416) 526-5667 or request a consultation today.
This article is general information and is not tax or legal advice for your specific situation. Cross-border tax rules and reporting thresholds are detailed and can change. Please consult Shandal CPA before acting on anything you read here.
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