In the third series installment, Cardinal Point’s John McCord looks at how the differing tax systems of the U.S. and Canada can lead to the risk of “double taxation” for expatriates when both countries tax the same income for the same tax year. The Canada U.S. tax treaty helps mitigate this risk as does the exchange of citizen and resident tax information between the two countries. Established in 1980, the treaty asserts that residency—not citizenship—is the most important factor. The article also discusses tax credits and tax-withholding guidelines set forth in the treaty.