Cross-border retirement income is usually where complexity peaks — private pensions, registered accounts, employer plans, each with its own rules. Government pensions are the welcome exception: for CPP, OAS, and US Social Security, the Canada–US treaty draws one of its cleanest lines.

The line is worth knowing precisely because people assume it must be complicated and get it wrong in both directions.

The residence-country rule

Under the treaty, social-security-type benefits such as CPP, OAS, and U.S. Social Security are generally taxable only in the recipient’s country of residence — and taxed under its own rules as if they were its own benefits.

So a retiree living in Canada who collects US Social Security generally pays tax on it to Canada, not the US — and Canada applies its own treatment to it, including relief provisions of its own. A retiree living in the US collecting CPP and OAS generally pays tax on those to the US, under the US’s own rules for social security-type income, which famously don’t tax the full amount for many recipients.

That’s the shape. The precise inclusion rates, the partial exemptions each country applies to the other’s benefits, and how the amounts land on each return are the verified-detail layer this article deliberately leaves to a preparer — the rates matter, and rates are exactly what shouldn’t be memorized from an article.

Where people go wrong anyway

Withholding is not the answer. In many treaty-covered cases, the payor-country withholding should be reduced or eliminated, but paperwork and default withholding settings can lag the treaty position. Recipients then assume “tax was taken, so it’s handled.” Wrong country, possibly wrong amount, and recovering misapplied withholding is its own small project. The treaty allocating a tax and the payroll system knowing about it are different things — a cousin of the broader autopilot myth in Assuming the Treaty Works on Autopilot — What the US-Canada Tax Treaty Does and Doesn’t Do for You.

The clean rule covers only the government benefits. Retirees extrapolate: “my pensions are taxed where I live.” This article does not cover private pensions, RRSP/RRIF withdrawals, government-service pensions, or lump-sum pension treatment. Private pensions, RRSP/RRIF withdrawals (RRSPs and the IRS: What the Treaty Handles Automatically — and What It Doesn’t ), and employer plans follow different treaty articles with different results — often source-country withholding plus residence-country tax with credits. Applying the government-benefit rule to everything is a tidy theory that produces untidy returns.

A US citizen is never just a resident. For a US citizen living in Canada, US citizenship-based filing continues regardless of where the treaty assigns the tax (I Moved Abroad — Do I Still Have to File US Taxes? ) — the income may end up taxed by Canada, but it still has to be handled correctly on the US return, not simply omitted.

For a retirement that spans the border, the government benefits are the easy chapter. The value of knowing that is knowing where the easy chapter ends.

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