Updated Checked by the Tax-Services.ca editorial team How we check
The first thing a cross border tax accountant will check is where you’re resident, because that decides which country taxes your worldwide income. Holding more than $100,000 of foreign property, measured at cost, is the second: it triggers a separate CRA form, the T1135. Get those two answers right and the rest of the file falls into place.
How do you pick a cross border tax accountant?
Nobody can promise you a good match from a search box, and we can’t rank or vouch for any firm. What we can do is give you a way to test the ones you find.
Ask whether they file both Canadian and US returns themselves or send one side out. Ask how many clients they have with your exact situation, whether that’s a cross-border commuter, a snowbird, a dual citizen or a Canadian with a US brokerage account. And ask them to explain, in plain words, how they’d decide your residency before they quote a fee.
Distance matters less than most people assume. A specialist two provinces away who does this all day can beat a generalist down the street. Still, you may want someone in your time zone, so it’s your call.
Which country treats you as a resident?
Canada looks at your ties: a home, a spouse or dependants, and the rest of your personal and economic connections. If both countries claim you, the Canada-US tax treaty has tie-breaker rules. The CRA says these start with a permanent home available to you in only one country, and then move to a test of which country your personal and economic ties are closer to.
One rule surprises people. For the treaty’s first residence test, the CRA treats holders of a US green card as US residents. And if the tie-breaker puts you in the other country, the Income Tax Act deems you a non-resident of Canada. That’s a big change.
Picture Elena, who lives in Windsor and works shifts in Detroit. Her home, her family and her bank accounts are all on the Canadian side. Her ties point to Canada, so she is generally taxed here on everything, and she reports the US wages on her Canadian return too. Move her family across the river and the answer could change. That’s why the residency question comes before any form.
Settle this before you file anything.
When must you file the T1135?
You file it if you’re a Canadian resident and, at any time in the year, the total cost of your specified foreign property was over $100,000. Note that cost is generally the adjusted cost base, not what the property is worth today. The CRA keeps the form and related guidance on its T1135 page.
| Cost of foreign property | How you report |
|---|---|
| $100,000 or less | No T1135 |
| Over $100,000, under $250,000 throughout the year | Part A, simplified: tick the type of property |
| $250,000 or more at any time | Part B, detailed: list each property |
Penalties can apply for filing late or leaving out information. The filing date and the penalty amounts weren’t confirmed for this page, so read the CRA’s T1135 page before you plan around them.
A worked example with a US brokerage account
Say you live in Ontario, earn $90,000 and hold US shares that cost you C$120,000. The T1135 is required, and Part A is enough as long as the cost stays under $250,000 all year. The income tax calculator puts your federal and Ontario tax at $17,034 on that income, before any foreign tax credit.
Now suppose you sell a US holding for a $95,000 gain. The capital gains tax calculator shows $17,451 of extra tax in Ontario on a $95,000 gain, with half the gain added to income. It doesn’t model foreign tax paid, and that’s the very thing a cross-border specialist is there to sort out.
Note one more thing about that example: the shares went from C$120,000 of cost to a bigger value, but the T1135 test still looks at cost. Selling one holding may even drop you back under $100,000 of cost for the next year, which is worth asking your accountant about.
What should you bring to the first meeting?
Bring both countries’ paperwork: your T4s and T5s, your US W-2 or 1099 slips if you have them, last year’s returns from each side, brokerage statements showing what each holding cost you, and anything showing where you live and where your family lives. A cross-border file with half the slips missing is the one that runs over the quote.
Mistakes and limits
The most common slip is assuming that tax withheld in the US settles things in Canada. It doesn’t. You still report the income here, and you may claim a credit for the foreign tax, which is a calculation in its own right.
The second is reading the $100,000 as market value. Cost is what counts, so a portfolio that has grown can cross the line without you noticing. Check the cost figures on your statements every year.
Our calculators cover Canadian tax only. Use the marginal tax rate calculator to see what an extra dollar costs you at home, then let your accountant handle the US side.
Where this information comes from
The T1135 thresholds and the residency rules come from the Canada Revenue Agency‘s foreign reporting pages and its income tax folio on residence status, and the tie-breaker text from the Canada-US tax convention published by the Department of Finance. Tax amounts come from our 2026 calculators. This is an independent guide, separate from any government body.
Frequently asked questions
Do I need a cross border tax accountant?
It's worth one if both countries may tax you, or if the cost of your foreign property passed $100,000. A plain Canadian return needs neither.
When do I have to file the T1135?
When the total cost of your specified foreign property was more than $100,000 at any time in the year. Check the CRA page for the due date.
Does a US green card affect my Canadian residency?
For the treaty's first residence test, the CRA treats green card holders as US residents. Tie-breaker rules then decide which country you belong to.
Is the $100,000 based on market value?
No. It's generally the cost amount, which is usually the adjusted cost base.
Does the accountant have to be near me?
We found no rule that requires it. Choose on experience with your situation first.
- How to choose a tax preparer in Canada
How to decide if you need a tax preparer, what a preparer does, the questions to ask before you hire one and where to find free help in Canada