Do I report income I earned before I moved to Canada?
Generally no. Canadian tax on your worldwide income starts on the date your residency begins, so income arising before that date is outside the Canadian base, although it may still have to be disclosed for other purposes such as working out prorated credits and benefit entitlements. The first return is a part-year return: it covers the period from arrival to the end of the year. The date itself therefore does real work, and it is a question of fact, established by where your home, your family and your ties actually were, rather than by the stamp in your passport.
What date does my Canadian tax year start as a newcomer?
On the date you became a resident, which is when your significant ties to Canada were established rather than when you first landed. A trip to look for a flat is not usually the start; arriving with your family and a lease or a purchase generally is. Because the personal credits on the first return are prorated to the part of the year you were resident, that date changes the tax as well as the period covered. Settle it with documents, such as the lease, the employment start and the removal of ties elsewhere, and record the reasoning, because it can be asked about later.
Do I have to report my overseas accounts on my first return?
The foreign property reporting that applies to Canadian residents does not apply for the first year. It begins in the second year of residence, and it is the one genuine concession a newcomer gets. It is also the one most often missed, because the relief in year one creates the impression that nothing was ever going to be required. Income from those foreign assets is a different matter and is reportable from the residency date onwards. So the pattern is income from arrival, and then the asset reporting a year later, which is the foreign property obligation catching up with you.
Will Canada tax the whole gain on property I owned before arriving?
No. Property you brought with you is treated as though you had acquired it on the day your residency began, at its value that day. The gain that accrued while you lived elsewhere is therefore outside the Canadian base, and only the movement in value from arrival onwards is Canada's to tax when you sell. This is why the arrival-day value of everything you already owned matters, and why it should be established while the evidence is fresh. Reconstructing what a property or a portfolio was worth years after the event is possible, but it is harder and easier to dispute.
Can I claim benefits in my first year in Canada?
Usually yes, but the claims run on information the return does not by itself supply. Income-tested benefits are calculated on household income for a period that includes the months before you arrived, so the amounts you and your spouse earned abroad have to be provided even though Canada does not tax them. The first return, the residency date and that household income statement therefore work together, and a claim made without them tends to stall. Personal credits on the return itself are prorated to the part of the year you were resident, so the first year's result looks different from every later one.
What proof do I need of what my property was worth on arrival?
Whatever an independent person would accept for that kind of asset. For listed shares and funds, the price on the date, taken from the exchange or the statement, with the exchange rate used to convert it recorded alongside. For a home or a let property, a valuation prepared for that date rather than an estimate produced long afterwards. For an interest in a private company, a reasoned valuation. Keep the working and not just the figure: the number may not be used for years, and by then whoever defends it will be relying entirely on what you wrote down at the time.
Is double taxation legal?
Yes. Nothing prevents two countries from taxing the same income under their own domestic law — each is exercising its own jurisdiction. What treaties and credit systems do is relieve the outcome rather than prohibit the charge, and relief is generally something you must claim on a return or a form, not something applied automatically. Miss the claim and the double charge stands. Double taxation explains the mechanism.
Do Canada and the United States share tax information?
Yes, through more than one channel. The treaty has an exchange-of-information article that supports both routine and on-request exchange. Separately, an intergovernmental agreement has Canadian financial institutions identify US-reportable accounts and report them to the CRA, which passes them to the IRS, with the reverse flow for Canadian residents. Most other country pairs use the Common Reporting Standard for the same purpose. See FATCA reporting.