How do US-Canada cross-border taxes work?

US-Canada cross-border taxation is one of the most common and complex international tax scenarios. Both countries tax their residents on worldwide income, and both have extensive tax systems that can create significant overlap. The US-Canada Tax Treaty, along with the Totalization Agreement, provides the framework for resolving these overlaps.

If you are a US citizen or green card holder living in Canada, you must file tax returns in both countries. Canada taxes you as a resident on your worldwide income, and the US taxes you as a citizen on your worldwide income. To prevent double taxation, you can claim the Foreign Tax Credit in the US for Canadian taxes paid, and you may also be able to claim credits in Canada for any residual US tax.

The US-Canada Tax Treaty provides specific rules for different types of income. Employment income is generally taxed only in the country where the work is performed. Pension income may be taxed in both countries but with reduced rates. Investment income such as dividends and interest may be subject to reduced withholding rates (typically 15% for dividends, 10% for interest).

Registered retirement accounts present particular challenges. Canadian RRSPs and RRIFs are treated differently under US and Canadian law. Under the treaty, you can elect to defer US tax on income accruing in an RRSP, but you must file Form 8891 (now reported on Form 8938). Contributions to an RRSP are not deductible for US tax purposes unless funded with Canadian-source employment income.

The Totalization Agreement between the US and Canada determines which country's social security system applies. Generally, you pay into the system of the country where you work. The agreement also allows you to combine work credits from both countries to qualify for benefits.

US-Canada cross-border taxation requires expertise in both tax systems. At Zenith Financial, we specialize in this corridor and ensure optimal tax positioning in both countries.