Do I file in Canada or the United States first?
Order matters more than people expect, because the country giving a credit needs to know what the other one actually took. In broad terms the first claim belongs to the country where the income arises or where the work was done, and the other country taxes you on your worldwide income and relieves the double charge with a credit. So the source-country figures have to be settled before the residence-country return can be completed properly. The complication in this corridor is that Canada taxes on residence and the United States taxes its citizens wherever they live, so a great many people sit inside both systems at once and neither return is optional.
I am a US citizen living in Canada, do I file twice?
Yes. A United States citizen files there every year regardless of where they live, and files in Canada as well once resident in Canada. Two returns covering the same income is the normal state of affairs in this corridor, not a sign that something has gone wrong. The double charge is relieved rather than prevented: one country credits what the other was properly entitled to take. What causes real trouble is treating the two returns as independent. Positions taken on one drive the credit available on the other, the same income is measured under two different sets of rules, and preparing them in the wrong order usually means amending one of them.
I live in Canada and work in the United States, who taxes the wages?
The country where the work is physically performed generally has the first claim on employment income, so wages earned in the United States are taxed there. Canada then taxes you on everything as a resident and credits the United States tax properly payable on those wages. Properly payable is the operative phrase: a credit follows what the other country was entitled to take, not what happened to be withheld, so over-withholding is recovered where it was collected rather than by inflating the Canadian credit. Pay periods straddling a move, bonuses paid after a change of residence, and share awards earned over several years all have to be split by where the work was done.
Does the treaty stop my state from taxing me?
Not necessarily. A treaty binds the two national governments, and a state is not automatically bound by it. Some follow the federal treatment and some tax on their own rules as though no treaty existed. The result is a charge the treaty did not contemplate, which your home country may not credit in full, because home credit rules do not always treat sub-national tax the same way as national tax. Check the particular state's position before assuming relief, and before accepting an assignment or a payroll arrangement that makes you taxable in a state you had not considered. Workdays, property and a period of earlier residence can each be enough.
Why do I still owe tax at home after paying tax abroad?
Because a credit is capped at the lower of the two charges. Where the country giving the credit taxes the same income at a higher effective rate, it credits what the other country took and collects the difference. Nothing has gone wrong. Relief from double taxation means you should not pay twice on the same income, not that you pay only the cheaper of two systems. Two things make that balance larger than expected. Credits are usually computed separately by category of income, so a surplus on one category cannot always relieve a shortfall on another. And the two countries measure the same income differently, so the figures being compared are not the same figures.
Can I stop filing US returns once I am resident in Canada?
No, not by becoming resident elsewhere. United States filing obligations follow citizenship, so moving to Canada and becoming resident there adds a Canadian return rather than removing the American one. Residence does change a great deal else: which country has the first claim on particular income, which reliefs are open to you, and what has to be disclosed about accounts and holdings on each side. Ending the United States obligation is a separate and consequential step with tax consequences of its own, and it does not happen as a by-product of a move. The workable approach is to treat both returns as one annual exercise.
Which countries have a tax treaty with the United States?
Around sixty, including Canada, the United Kingdom, India, Australia and most of western Europe — but the list matters less than the terms, because each treaty caps rates and allocates income differently. Two countries with treaties can produce opposite answers on the same pension or the same royalty. What decides your position is the specific article covering your income type. See our country guides.
Which country do I pay tax to first?
Generally the source country — where the income arises — taxes first, often by withholding before you receive it. Your country of residence then taxes the same income and credits what the source country took. That order is why timing matters: a residence-country return filed before the source-country tax is settled has nothing to credit yet. Getting the sequence right is most of the work. See international tax planning.
