US-Canada Double Tax Avoided: A Worked Example of Foreign Tax Credits on $120K of Cross-Border Income

You're a US citizen living in the GTA, earning a C$120,000 salary from a Canadian employer. You know both countries want to tax that income. You've heard the Foreign Tax Credit prevents double taxation. But what does the math actually look like?

This is the full two-country calculation — not the theory, the actual numbers. We'll compute your Canadian federal and Ontario tax first, then your US federal tax, then show exactly how Form 1116 wipes out the US bill and generates a carryforward. Every bracket and rate is labelled with the country, the tax year, and the source.

The Scenario: US Citizen, Ontario Resident, C$120,000 Salary

Meet the profile: a US citizen who has lived in Mississauga for five years, working for a Canadian employer. Single filer. No US-source income, no investment income — just a straightforward C$120,000 annual salary. The goal is to show the core FTC mechanic cleanly before adding complexity.

Step 1: Canadian Tax — Federal + Ontario on C$120,000

Canada taxes first because you're resident in Canada. Your Canadian employer deducts income tax at source throughout the year. Here's the breakdown.

Federal Income Tax

Ontario Provincial Tax

Ontario applies a two-tier surtax on top of basic provincial tax: 20% on the amount over $5,315 and 36% on the amount over $6,802. This is a tax-on-tax — it effectively pushes Ontario's marginal rate above the headline bracket rates, which is why the combined federal-plus-Ontario top rate reaches 53.53% at higher incomes.

Step 2: US Federal Tax on the Same Income

As a US citizen, you owe US federal tax on worldwide income regardless of where you live. Your C$120,000 salary converts to approximately US$87,600 at the 0.73 rate. After the standard deduction of US$15,700, your US taxable income is US$71,900.

Without any credit mechanism, you'd pay this US$10,733 on top of the C$29,060 you already paid Canada. That's roughly C$43,760 total on C$120,000 of income — a 36.5% combined rate across two countries. This is the double-taxation problem the treaty and the FTC exist to solve.

Step 3: The Foreign Tax Credit (Form 1116) Eliminates the US Bill

Form 1116 — Foreign Tax Credit — lets you credit the income taxes paid to a foreign country against your US tax liability. Both Canadian federal tax and Ontario provincial tax qualify as creditable income taxes. CPP contributions and EI premiums generally do not (they're social insurance, not income tax).

The FTC limitation formula

The IRS doesn't let you credit unlimited foreign taxes — there's a cap called the FTC limitation. The formula under IRC §904(a):

In our scenario, all income is foreign-source (Canadian salary, no US income). So the ratio is 1.0, and the limitation equals the full US tax:

The Canadian tax you paid is nearly double the US tax on the same income. The FTC uses US$10,733 of your Canadian tax to zero out the US bill. The remaining US$10,481 of “excess” Canadian tax credits carry forward for up to 10 years (or back 1 year) under IRC §904(c). That carryforward is real money — if you earn US-source income in a future year, or take an RRSP withdrawal that generates US tax, the carryforward can offset it.

The Bottom Line: What You Actually Pay

You pay Canada's rate and nothing more. The FTC saves you roughly C$14,700 that would otherwise have gone to the IRS on top of what you already paid the CRA and Ontario. This is the core double-taxation relief mechanism under Article XXIV of the 1980 Canada-US Tax Convention.

Why Canadian Tax Is Almost Always Higher Than US Tax

This isn't a fluke of the $120K income level. Canadian combined federal-plus-provincial rates exceed US federal rates at nearly every income level for Ontario residents. The top combined Ontario rate is 53.53% (federal 33% + Ontario 13.16% + surtaxes) vs. the US top federal rate of 37%. Even at moderate incomes, Canada's combined rate outpaces the US:

The practical implication: for virtually any Canadian-resident US citizen earning employment income in Canada, the FTC will eliminate the US tax liability and generate excess credits. This is not an edge case — it's the standard outcome.

Form 2555 (FEIE) vs. Form 1116 (FTC): Why the Credit Usually Wins

The Foreign Earned Income Exclusion (Form 2555) is the other double-taxation relief tool. The 2026 FEIE threshold is US$132,900. Since our taxpayer's income (US$87,600) falls below this threshold, the FEIE would also zero out the US tax. So why prefer the FTC?

The FEIE's biggest cost is invisible on day one: it wastes the excess Canadian tax credits. Under IRC §911(d)(6), you cannot claim the FTC on income you've excluded. The US$10,481 of excess credit that the FTC generates simply vanishes under the FEIE approach.

Where this matters: three years from now, you take a $50,000 RRSP withdrawal. The FTC carryforward from this year can offset US tax on that withdrawal. Under the FEIE? No carryforward exists, and RRSP withdrawals aren't “earned income,” so the FEIE can't exclude them either. You'd pay US tax on the withdrawal with no offset.

The Treaty Basis: Article XXIV of the Canada-US Tax Convention

The legal foundation for this relief is the 1980 Convention Between Canada and the United States of America with Respect to Taxes on Income and on Capital (the “Canada-US Tax Treaty”). Article XXIV specifically requires each country to allow its residents a credit for income taxes paid to the other country:

• Article XXIV(2)(a): The US shall allow a US citizen or resident a credit against US tax for the income tax paid or accrued to Canada.
• Article XXIV(2)(b): Canada shall allow a Canadian resident a deduction or credit for the income tax paid to the US.
• Article XXIV(4): For the purpose of the credit, the income tax paid to the other country is deemed to include taxes that would have been paid but for a limitation in the domestic law — this preserves the credit mechanism even in cases of domestic exemptions or exclusions.

The treaty doesn't create the FTC — that's IRC §901 and Form 1116 on the US side, and ITA section 126 and Form T2209 on the Canadian side. But the treaty obligates both countries to provide the relief, which prevents either country from unilaterally removing it.

The Canadian Side: What If You Also Owe US Tax?

In our scenario, the FTC eliminated all US tax — so there's no US tax paid to claim on the Canadian return. But if the situation were reversed (US-source income taxed by the IRS, claimed as a credit against CRA), the mechanism is Form T2209 — Federal Foreign Tax Credits.

T2209 works the same way in principle: Canadian tax on the foreign income minus the creditable US tax paid, capped at the Canadian tax on that income. The provincial credit flows through Form T2036 (Provincial or Territorial Foreign Tax Credit). If you earn US-source consulting income, take an IRA distribution, or have US rental income, these forms become critical — they prevent the double-tax from the Canadian side.

Cross-Border Treatment of Retirement Accounts

The salary-only scenario above is the simplest case. Real cross-border lives involve retirement accounts — and each one has its own treaty treatment:

The TFSA is the landmine. US citizens in Canada should generally avoid contributing to a TFSA — the IRS reporting burden (Forms 3520 and 3520-A, penalties starting at US$10,000 per missed form per year) outweighs the Canadian tax-free benefit. Maximize your RRSP instead — the treaty protects it on both sides.

Cross-Border Withholding Tax Rates Under the Treaty

When income crosses the border — dividends, interest, pensions, royalties — the source country withholds tax. The treaty reduces these rates below the default domestic rates:

These reduced withholding rates interact with the FTC: the lower the withholding at source, the more tax the residence country collects — but the total remains the same because the FTC credits the withholding against the residence-country tax. The treaty just shifts who gets the first cut.

Dual-Residency Tie-Breaker: Article IV

A US citizen living in Canada is resident in both countries under domestic law — the US taxes on citizenship, Canada taxes on residency. The treaty resolves this through Article IV tie-breaker rules. For individuals, the tie-breaker hierarchy is:

1. Permanent home — where you maintain a home available to you. If you rent in Mississauga and have no US home, Canada wins.
2. Centre of vital interests — where your personal and economic ties are closer (family, work, social life).
3. Habitual abode — where you spend more time.
4. Citizenship — last resort.

The tie-breaker matters for treaty benefits on specific income types. For most US citizens living full-time in Canada with a Canadian employer, Canada is the treaty residence — which gives Canada first taxing rights on employment income and preserves the FTC structure we've worked through above.

Don't Forget: The Reporting Obligations Beyond Form 1116

Zeroing out the US tax bill is the goal. But the filing obligations don't disappear just because you owe $0. A US citizen in Canada typically faces:

• Form 1040 — required every year regardless of tax owing
• Form 1116 — to claim the Foreign Tax Credit
• FinCEN 114 (FBAR) — if aggregate foreign accounts exceed US$10,000 at any point during the year
• Form 8938 (FATCA) — if foreign financial assets exceed US$200,000 at year-end or US$300,000 at any point (for those living abroad)
• Form 8833 — treaty-based return positions (e.g., claiming RRSP deferral under Article XVIII)
• Forms 3520 / 3520-A — if you hold a TFSA (treated as a foreign trust by the IRS)

The penalty for a missed FBAR is up to US$10,000 per account per year (non-willful) or the greater of US$100,000 or 50% of the account balance (willful). A missed Form 3520 starts at US$10,000. These penalties apply even when you owe $0 in tax. Filing is not optional.

When the FTC Doesn't Fully Eliminate US Tax

The C$120K Ontario example produces a clean $0 US tax result because Canadian rates are higher. But there are scenarios where the FTC falls short:

• US-source income mixed with Canadian income: If you earn US consulting fees or US rental income, those aren't “foreign-source” income for the FTC limitation — the Canadian tax credits can't offset US tax on US-source income. You'd owe US tax on the US-source portion.
• Alternative Minimum Tax (AMT): The FTC is limited under the AMT rules (IRC §59(a)). If the AMT applies, the FTC limitation is calculated differently, and you may owe AMT even with excess Canadian tax credits.
• State taxes: Form 1116 credits federal taxes only. If you maintain US state-tax residency (e.g., you own property in a state with income tax), the state may tax your worldwide income without crediting Canadian provincial tax. This is uncommon for full-time Canadian residents but catches snowbirds and dual-state filers.
• Income-category mismatch: Form 1116 separates income into categories (general, passive, etc.). Canadian tax on salary goes into the “general” basket; Canadian tax on investment income goes into the “passive” basket. You can't use excess general-category credits to offset passive-category US tax. The baskets don't mix.