Does a green card mean I pay US tax on worldwide income?
Yes. A green card holder is taxed by the United States as a resident, which means income from all sources: salary, business profits, rent, interest, dividends and gains, wherever earned and wherever the money stays. Two consequences follow that people rarely expect. The obligation does not pause when you leave, so a card held while living in another country generally keeps the filing requirement alive until the status is formally given up, and giving it up has tax consequences of its own. And residence brings information reporting on accounts and assets held outside the country, which is separate from the tax return and carries its own exposure if it is missed.
How does the substantial presence test make me a US resident?
It counts days. Presence in the United States is added up across the current year and earlier years on a weighted basis, so days further back count for less but still count. That is what makes the test catch people who have never lived there, because a pattern of regular business trips or long visits can accumulate into residence without any single year looking unusual. If the count is met, the United States taxes you as a resident on worldwide income for that year, subject to any exception or treaty claim you are entitled to make and actually do make. Because the test is arithmetic, it can be forecast, and forecasting it is far cheaper than unwinding it.
I left the US but kept my green card, so must I file?
Almost certainly, yes. Immigration status and tax status are settled separately, and the card generally keeps you inside the resident regime until it is formally abandoned through the proper process. Living elsewhere, paying tax elsewhere and having no American income do not by themselves end the obligation. Two things follow from that. Years spent abroad with no filing are open years, and they tend to surface at the worst possible moment, such as a renewal, a citizenship application or a property sale. And giving up the status is itself a tax event that wants planning before it happens rather than after, because the sequence and the date both affect the outcome.
Do I have to report my Canadian accounts to the US?
If the United States taxes you as a resident then yes, and the reporting is wider than the tax. The American system attaches information filings to accounts and assets held outside its borders, each with its own threshold, its own deadline and penalties that can apply even where no tax is owed at all. Ordinary Canadian products are caught, including chequing and savings accounts, investment accounts, some registered plans and interests in private companies. The mistake we see most often is the person who has filed returns diligently but never the accompanying information filings, and whose years are therefore incomplete rather than late. Catch-up routes exist, and they are easier used before an enquiry arrives.
Can I be a US resident alien and a Canadian resident together?
Yes, and it is common. Each country applies its own domestic test and both can be met at once: a green card or a pattern of presence on one side, ties or a statutory rule on the other. Where that happens, both countries claim worldwide income, and the treaty between them decides which residence governs for treaty purposes through an ordered series of tests. The claim does not remove either country's domestic classification. It allocates taxing rights and settles which country gives credit for the other's tax. Both returns still have to be prepared, and prepared together, because the figures in each depend on what the other one does.
When does my first year as a resident alien actually start?
Rarely at the start of January, which is why the first year is the hardest to file. Where residence begins part way through, the year splits: one part is taxed under the non-resident rules on American-source income, and the remainder under the resident rules on worldwide income. Income then has to be allocated across that date on a basis the return can explain, so employment by work performed, investment income by receipt, and gains by the date of disposal. The practical point is that the date needs fixing from records before anything is computed, because every figure derives from it. Get the date wrong and the whole return is wrong consistently.
Do dual citizens pay taxes in both countries?
Both countries can have a claim, but paying double taxes on the same dollar is the exception rather than the rule. The United States taxes its citizens wherever they live; Canada, India and most others tax on residence. So a dual citizen living in one of them often files in both — a resident return in one, a citizen return in the other — while the credit and exclusion rules mean the total is usually close to the higher of the two, not the sum. Filing twice is not paying twice. See two returns as a dual citizen.
Do I get credit for all of the foreign tax I paid?
Only up to your own country's tax on that same income, and only for tax you were legally obliged to pay. Two consequences follow. Living somewhere that taxes you more heavily than your residence country does leaves an excess that becomes a carryover rather than a refund. And withholding suffered above the treaty rate is not creditable — the route back to that money is a refund claim in the country that took it. See claiming the credit.
