I am a US citizen living in Canada — does the treaty help?
In places, but less than you might expect. The treaty allocates taxing rights between the two federal governments and provides for credit relief, and a US citizen resident in Canada can rely on much of that machinery. The saving clause is the limit: it preserves the United States' right to tax its own citizens broadly as if the treaty were not there, so several reliefs a Canadian resident could claim are cut back for a citizen. The practical result is that residence work and credit computation carry more weight than the article itself. Read the clause before relying on an exemption.
Both countries treat me as resident — how is that resolved?
Through the treaty's residence tie-breaker. Domestic law in each country can make the same person resident in both, and the treaty does not remove either claim; it decides, for treaty purposes, which country is treated as the country of residence. The test runs in order through factors such as a permanent home and the centre of personal and economic relations, and stops at the first one that decides. It is a factual exercise, so the file has to hold the facts: where the home is, where the family lives, where the work is done. Assemble that evidence before taking the position.
Does the treaty stop a US state from taxing me?
Generally not. The treaty binds the federal governments. US states and Canadian provinces set their own rules and are not equally constrained, so a state can tax income the treaty has already assigned elsewhere for federal purposes. People meet this after they have settled the federal position and assume the rest follows. It does not. Check the rules of the specific state or province separately, and expect the answer to differ from the federal one. Where both apply, the mismatch is a real cost that has to be planned for rather than argued away.
Why is tax still withheld on my US income after a treaty claim?
Because the treaty sets reduced withholding rates rather than removing withholding. A valid claim lowers the deduction to the rate the relevant article allows; it does not usually take it to nothing. Two further things go wrong in practice. The payer must hold the documentation before it pays, so a claim made later becomes a refund exercise. And the reduced rate depends on the type of income, so one payer handling dividends, interest and royalties may apply different rates to the same recipient. Check what the payer holds, and what it thinks it is paying you.
Do I have to disclose a treaty position on my return?
Often yes, and it is a step that is frequently skipped. Claiming that a treaty overrides domestic law is a position, and a position generally has to be visible on the return that takes it. Leaving it silent does not make it safer; it makes it undocumented, which is worse if the year is later examined. Keep three things together in the file: the article relied on, the facts that make it apply, and the computation it changes. That package is what answers a query, and it is far easier to build while the return is being prepared.
Does the treaty mean I only file in one country?
No. Allocating a taxing right is not the same as removing a filing obligation. The treaty decides which country taxes an item of income and at what maximum rate, and provides credit relief where both still reach it — but each country's own law decides who must file. Cross-border clients routinely file in both and settle the double tax through credits rather than through exemption. Plan the two returns in sequence, because the credit is computed in the country that taxes second and depends on what the first return actually showed.
Is double taxation illegal?
It is legal. Two countries can each have a valid claim on the same income — one because the income arose there, the other because you live there — and nothing prohibits both from exercising it. What exists instead is relief: tax treaties allocate the claim, and domestic law gives a credit for foreign tax paid. The relief is not automatic, though. It is claimed on a return, and unclaimed relief is simply lost. See how double taxation is relieved.
What does Form W-8BEN actually do?
It tells a US payer that you are not a US person and, where you are entitled, claims the treaty rate on the income they are about to pay you — so withholding comes off at the reduced rate rather than the statutory one. It goes to the payer or the broker, never to the IRS, and it expires, so a stale form is a common cause of over-withholding. Getting it in before payment is the difference between a lower rate and a refund claim. See Form W-8BEN.
