Does the Canada–US treaty mean my estate pays no US estate tax?
No, and that is the most common misunderstanding about it. The treaty does not exempt a Canadian estate from US estate tax. It supplies relief that reduces the tax: a credit pro-rated by reference to how much of the worldwide estate is situated in the United States, and a separate credit on qualifying transfers to a spouse. Both are claims. They are made on a US return, with the figures that support them, and an estate that files nothing gets neither. So the treaty changes the amount rather than the obligation, and the obligation has to be met before the relief can be had.
How is the treaty credit calculated for a Canadian estate?
By proportion. The relief is pro-rated using the ratio between the assets situated in the United States and the worldwide estate, so the credit tracks how much of the estate is exposed rather than the size of the exposure alone. Two consequences follow. The worldwide estate has to be valued, including assets the United States will never tax, because it is the denominator. And the ratio itself, not just the value of the American holdings, determines the relief, which is why a movement in the value of domestic assets can change the outcome on the US side.
Why must we value my mother's Canadian house for a US filing?
Because the relief is worked out as a proportion, and her Canadian assets sit in the denominator of it. The United States is not taxing the house. It is being asked to accept a credit calculated on the share the American holdings represent of everything she owned, and that share cannot be evidenced without valuing the rest. Executors find this intrusive, and it is the single most common cause of delay in these files. We identify at the outset which valuations are needed for the ratio and which are needed for the Canadian filings, because the two sets are commissioned for different purposes and the evidence expected differs.
Does leaving everything to my spouse remove the US estate tax?
Not by itself. The treaty provides a credit on qualifying transfers to a spouse, which can reduce the tax substantially, but it is conditional and it is claimed rather than automatic. Whether a transfer qualifies depends on how the property passes and on the terms of any trust it passes into, so the wording of the will and the way accounts are titled matter as much as the intention behind them. We look at the transfer as drafted, not as described, and where it does not qualify we say so while the documents can still be changed. On death, the claim is made on the US return with the supporting facts set out.
Can the US estate tax be credited against the Canadian tax on death?
The two systems are reconciled by credit, but they are not measuring the same thing. Canada taxes the accrued gain on a deemed disposition at death; the United States taxes the value of property situated there. One can be large while the other is small on the very same asset, so a credit does not always absorb the whole of the other tax. The order of work matters too, because a credit cannot be finalised until the tax it relieves has been assessed. We compute both sides together and set the reconciliation out on one schedule, so the executor can see where relief is genuinely available.
Do we have to file in the United States to claim treaty relief?
Yes. Both the pro-rated credit and the spousal credit are claims made on a US estate tax return, supported by the figures behind them, and neither is applied by default. Executors sometimes reason that because the relief will reduce the tax to nothing there is nothing to file, which inverts the position: the relief exists only inside a filing. Custodians holding the American assets take the same view in practice, since release generally waits on the US position being settled. The safe sequence is to value, file, claim, and then deal with the release of the assets.
Does the United Kingdom have a tax treaty with the United States?
Yes — the UK and the USA have one, and so do around sixty other jurisdictions including Canada, India, Australia, Mexico, Brazil and most of western Europe. The existence of a treaty is rarely the useful fact, though. Two people in two treaty countries can get opposite answers on the same pension or the same royalty, because what decides the outcome is the specific article for that income type and any limitation-on-benefits condition attached to it. See our country guides.
How does the treaty tie-breaker work when both countries say I am resident?
As a sequence, stopping at the first test that gives an answer: where you have a permanent home available; if in both or neither, where your centre of vital interests is; then habitual abode; then nationality; and if all of those tie, the two tax authorities decide by agreement. It is evidential rather than elective — you do not choose your treaty residence, you demonstrate it, which makes the record of homes, family and time the substance of the claim. See tie-breaking dual residency.
