Doing business across the Canada-US border sounds simple on paper. Two friendly countries, one of the world’s biggest trade relationships, and a long-standing tax treaty designed to make life easier for businesses operating in both places.
Then you actually try to run a foreign corporation across that border, and reality hits. Now it’s two tax authorities with different sets of rules and definitions of who owes what and when. One wrong move can mean paying tax on the same income twice or getting hit with penalties from a country you did not even know was watching.
In this post, we walk you through the real tax issues foreign corporations run into when operating between Canada and the United States, and what you need to understand to keep your business clean on both sides.
Why This Is More Complicated Than It Looks
Many foreign corporations assume that if they have a US company, the IRS handles them, and if they have a Canadian company, the CRA handles them. Easy.
It is not that easy. The moment your business starts earning income in the other country, or even just selling to customers there, you have a cross-border issue. Depending on what you are doing, both countries might want a piece of your profits.
The Canada-US Tax Treaty exists to prevent this kind of double taxation. It does a good job, too, but only if you understand how to apply it. Get the treaty wrong, miss a filing, or assume something does not apply to you, and you can end up in real trouble.
Permanent Establishment (PE)
If you remember one thing from this post, remember this. The single most important concept in Canada-US business taxation is something called a permanent establishment, or PE.
A permanent establishment is basically a fixed place of business in another country. An office. A factory. A warehouse. A construction project lasting more than 12 months. Even a dependent agent who regularly signs contracts in your name.
Why does it matter? Under the treaty, a US corporation owes Canadian income tax on business profits only if it has a permanent establishment in Canada. The same rule applies in reverse. A Canadian corporation only owes US federal income tax if it has a permanent establishment in the United States.
So if your US company is selling into Canada from across the border without any physical presence here, you are usually exempt from Canadian federal tax under the treaty. But, and this is the big but, you still have to file a return to claim that exemption. The CRA does not just trust you. You have to prove it.
The T2 Filing Requirement Catches Foreign Companies Off Guard
Here is something most US business owners miss. Even if your company owes zero Canadian tax under the treaty, you might still have to file a Canadian T2 corporate tax return.
This is called a treaty-based return. It is informational. You are basically telling the CRA, “Yes, we did business in Canada, but our activities are protected under Article VII of the treaty, so we owe no tax.” Without this filing, the CRA assumes you owe full tax and can come after you for it later.
The T2 is due six months after your fiscal year end. Late filing penalties apply. And the CRA has been sending more notices to US companies recently, asking why returns were not filed even for minimal Canadian activity. So if you have customers, agents, or any kind of presence in Canada, the safer move is to file.
The same logic applies to Canadian companies operating in the US. You may need to file a US 1120-F return even if you owe nothing, just to claim treaty protection.
State and Provincial Tax Is a Whole Separate Issue
This is the part that really blindsides foreign corporations. The Canada-US Tax Treaty applies to federal taxes only. It does not protect you from state taxes in the US or provincial taxes in Canada.
So you could be a Canadian company with no permanent establishment in the US under the treaty, meaning no US federal tax. But if you sell into California, New York, Texas, or any other state where you have what they call “nexus,” you might owe state corporate income tax, state sales tax, and state franchise taxes. Each of the 50 US states sets its own nexus rules, and many of them define it far more broadly than the federal PE standard.
The same goes for US companies in Canada. You might be exempt under the treaty, but if your activities create a nexus in Ontario, Quebec, or any other province, you may owe provincial tax separately. Most provinces follow federal rules, but there are exceptions, and the rules around GST or HST registration kick in once your sales hit $30,000 CAD a year.
So your cross-border tax planning is not done at the federal level. You also need to look at every state or province you touch.
Withholding Taxes on Cross-Border Payments
Another area where foreign corporations get tripped up is withholding tax. When money flows across the border, the country sending the money usually keeps a piece of it as withholding tax.
The treaty reduces these rates significantly compared to the default rates.
For dividends, the standard Canadian withholding rate is 25 percent. Under the treaty, it drops to 15 percent in most cases and to 5 percent if the receiving company owns at least 10 percent of the payer’s voting shares. The US has similar rules in reverse.
For interest, the treaty eliminates withholding tax entirely on most arm’s length interest payments between US and Canadian companies.
For royalties, the treaty caps withholding at 10 percent, and some types of royalties (such as software royalties) are exempt entirely.
To claim these reduced rates, you must file the correct forms. US payers need a W-8BEN-E from the Canadian recipient. Canadian payers need NR301 from the US recipient. Skip these forms and the default 25 or 30 percent withholding kicks in, and getting that money back takes time and paperwork.
What Section 899 Could Change in 2026 and Beyond
There is a wrinkle worth knowing about. As of mid-to-late 2025, the US Congress advanced Section 899, a provision that would aggressively increase US withholding tax rates on payments to countries it considers to have “unfair” or discriminatory tax policies.
Canada was a primary target because of its digital services tax, a threat so severe that the Canadian government has since committed to rescinding the tax to avoid the fallout.
If Section 899 provisions are officially triggered against a non-compliant country, withholding rates on dividends, interest, and royalties flowing from the US could climb by 5 percent per year. So, a dividend currently enjoying a 15 percent treaty rate could climb to 20 percent in year one, then 25 percent the next.
What does this mean for you? If you are doing business across the border, watch this space closely. The rules are shifting, the US is playing hardball, and the cost of getting it wrong is going up.
Branch Profits Tax
If a US corporation operates in Canada through a branch rather than a separate Canadian subsidiary, Canada imposes a 25 percent branch profits tax on after-tax profits not reinvested in Canada. The treaty reduces this to 5 percent with a $500,000 lifetime exemption.
The US applies the same kind of branch profits tax to Canadian corporations operating through US branches at a standard rate of 30 percent. Again, the treaty drops this to 5 percent.
This is one reason many cross-border businesses choose to set up a separate subsidiary in the other country rather than operating a branch. The tax treatment is often much cleaner.
How to Stay on Top of It All
Here is the honest truth. Canada-US cross-border tax is one of the most complex areas in business taxation. The treaty is helpful but also detailed. Filing requirements exist even when no tax is owed. State and provincial rules add another layer. Withholding rates depend on the right paperwork being filed at the right time.
If you are running a foreign corporation that touches both countries, the cost of getting expert help is usually less than the cost of getting it wrong. A missed T2 filing. A botched W-8BEN-E. A state tax surprise from California. A misclassified branch versus a subsidiary. These mistakes add up fast.
The Tax Whiz works with foreign corporations operating between Canada and the US every day. We handle treaty-based filings, T2 returns, cross-border withholding setup, and the kind of strategic structuring decisions that determine whether your business pays tax once or twice. If you are operating across the Canada-US border and want to make sure you are doing it right, get in touch through the Tax Whiz website and let us look at your situation.