US-Canada Cross-Border Tax
Working with US clients or spending time in the US triggers a parallel US tax system on top of Canadian residency. The Canada-US Tax Treaty resolves most double-tax issues, but only if you actually invoke it: Form 8833 for treaty positions, W-8BEN to stop 30% withholding, Form 8840 for snowbirds, and a CPT-56 to avoid US Social Security.
Last reviewed:
Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact CRA. Read our editorial scope →
1. The treaty framework
The Canada-US Tax Convention (1980, as amended through the Fifth Protocol 2007) governs tie-breaks. Article IV resolves dual residency. Article VIItaxes business profits only where there is a Permanent Establishment (PE) in the source country. Article XV covers employment income. Article XXIVgrants foreign tax credits.
2. Permanent Establishment — when US clients trigger US tax
A Canadian contractor invoicing US clients from Toronto has no US tax obligation on the business profit — Article VII says it is taxable only in Canada. PE is triggered by a fixed place of business in the US (office, branch) or by services performed in the US for >183 days in any 12-month period (Article V(9)). Without a PE, the W-8BEN-E claim stops US withholding at source.
3. FBAR — the $10,000 aggregate trap
US persons (citizens, green-card holders, residents) with foreign financial accounts whoseaggregate peak balance exceeded US$10,000 at any moment in the year must file FinCEN Form 114 (FBAR) by April 15 (auto-extended to October 15). Aggregate means total across all accounts — a $7k chequing + $4k TFSA crosses the line. Penalties for wilful non-filing start at US$10,000 per account per year.
4. The Substantial Presence Test
A non-US-citizen Canadian becomes a US tax resident if days in the US over three years satisfy:
Current-year days + ⅓ × prior-year days + ⅙ × second-prior-year days ≥ 183 days
Worked example. Snowbird Margaret spends 130 days in Arizona in 2025, 130 in 2024 and 120 in 2023. Test: 130 + 43.3 + 20 = 193.3 ≥ 183. Margaret is a US person unless she files Form 8840 (Closer Connection Exception) by June 15.
5. Form 8840 — closer connection
Available if (a) you spent < 183 days in the US in the current year and (b) you maintain a closer connection to Canada (home, family, bank accounts, driver's licence). File 8840 annually. If you exceed 183 days in the current year, only the treaty tie-breaker (Form 8833 with Article IV) can save you.
6. Totalization Agreement & CPT-56
A Canadian working temporarily in the US for ≤ 60 months remains in the Canadian CPP/EI system instead of paying US Social Security and Medicare. Request a Certificate of Coverage (Form CPT-56) from the CRA and give it to the US employer. Without it the worker pays 15.3% FICA on top of CPP — and recovery is administratively difficult.
7. USD invoicing & FX conversion
Convert each USD receipt at the Bank of Canada daily rate on the day of receipt (or, by election, the BoC annual average for the year). Be consistent: switching between daily and average across years is acceptable only with sound justification (CRA Folio S5-F4-C1).
8. US withholding on Canadian recipients
Default US withholding is 30% on dividends, royalties, rents and certain services. Treaty rates: 15% on portfolio dividends (Article X), 0% on most royalties (Article XII), 0% on interest (Article XI as amended). Claim by giving the payer a W-8BEN (individuals) or W-8BEN-E (entities). If withholding occurred without the form, file Form 1040-NR or Form 1120-F to recover.
Last reviewed: