My country has no treaty with theirs — is relief possible?
Usually some relief exists, and it comes from your own country's statute rather than from an agreement. Domestic law in most systems allows foreign tax on foreign-source income to be credited against domestic tax on the same income, or at least deducted in computing it. That is unilateral relief, and in a corridor with no treaty it is the whole of what you have. Expect it to be narrower. Its conditions are set by one country alone, the foreign levy has to satisfy that country's own tests, and there is no counterpart obliged to do anything from the other side. So the first step is to read the domestic provision rather than assume treaty-style outcomes.
What is unilateral relief and how does it differ from treaty relief?
Unilateral relief is given by a country's own law for foreign tax, whether or not a treaty exists. Treaty relief is given because two countries agreed how to divide the income between them. Three differences matter in practice. A treaty can stop the other country taxing at all, whereas unilateral relief cannot; it only reduces your own country's tax on income the other has already taxed. A treaty has a procedure for the two authorities to resolve a disagreement, and unilateral relief has none, so a dispute is with one authority on its own terms. And a treaty covers named taxes and supplies tie-breakers, while a domestic provision defines its own scope.
Is every foreign tax creditable under domestic relief rules?
No, and this is where non-treaty files most often come apart. A domestic relief provision typically requires the foreign levy to be a tax on income of a kind the relieving country recognises, to be imposed on the person claiming relief, to relate to income that country treats as foreign-source, and to be finally paid rather than merely charged. A levy that is really a turnover charge, a licence fee, or a tax on a different person falls outside it. So does foreign tax on income your own country regards as domestic-source. Check the levy against the statute's wording before building a claim on it.
Can I get the foreign withholding reduced without a treaty?
Not through a treaty rate, because there is none. In a non-treaty corridor the payer withholds at the source country's own statutory rate, and any reduction has to come from that country's law: an exemption for a type of income or type of recipient, a refund procedure on assessment, or the ability to file there and be taxed on a net amount rather than a gross one. That is worth checking, because withholding applied to a gross payment routinely exceeds the tax that would be due on the profit. Your own country's unilateral relief then applies to whatever foreign tax finally remains, capped at its own tax on that income.
Who decides a residence dispute if there is no treaty?
Nobody jointly. Each country applies its own residence test and reaches its own answer, and if both answers are yes, both stand. There is no tie-breaker and no procedure obliging the two authorities to talk to each other. That leaves two routes. Manage the facts so that only one test is met, which means dealing with the domestic criteria of each country separately and in advance. Or accept dual residence and use each country's unilateral relief as far as it goes, knowing it relieves foreign tax on foreign income and does nothing for income each country treats as its own. Non-treaty residence is a planning problem, not a claim.
Does unilateral relief cover state, provincial or municipal taxes?
It depends entirely on the wording of the provision, and it is worth checking rather than assuming. Some domestic relief rules extend to income taxes imposed by a sub-national government. Others are confined to taxes imposed by a national government, which can leave a real levy with no relief at all. That is a difference from the treaty world, where the taxes covered are listed and the answer can be read off the text. Where a sub-national tax falls outside the relief provision, the remaining questions are whether it is deductible in computing income instead, and whether the underlying income can be arranged so that it is not exposed.
What happens if the two countries disagree about which of them can tax me?
The treaty has a procedure for exactly that. You apply to the competent authority in your residence country, which takes the case up with its counterpart, and the two negotiate a position that removes the double taxation. Some treaties add binding arbitration if they cannot agree. It is slow and it runs on documents, so the practical work is preserving the record and filing protective claims while the clock runs. See our treaty work.
How would a foreign tax authority know I am resident there?
Mostly from information you or your bank already provided. Account-opening forms ask you to self-certify tax residence, and that certification is reported between authorities under the Common Reporting Standard or, for US accounts, under the FATCA framework. Beyond that: employer and payroll filings, property registries, immigration records and the tax filings of anyone who paid you. The realistic planning assumption is that the data arrives. See FATCA and information reporting.
