How does Canada treat dual citizenship?

Canada has recognised dual citizenship since the federal Citizenship Act came into force on February 15, 1977. Before 1977, the previous Canadian Citizenship Act of 1947 generally required Canadians who acquired another nationality to renounce Canadian citizenship, a rule that produced many instances of unintended loss of citizenship. The 1977 Act removed this rule and allowed Canadian citizens to hold one or more other nationalities without affecting their Canadian status. Estimates suggest that about 2 to 3 million Canadians currently hold dual or multiple citizenship.

The federal Citizenship Act treats dual citizens identically to citizens with only Canadian nationality for almost all federal purposes. Dual citizens have the right to vote in federal elections (after the Frank v. Canada decision of 2019 removing residency-based restrictions for Canadians abroad), the right to a Canadian passport, the right to consular services from Canadian missions abroad, the right to enter and remain in Canada under section 6 of the Canadian Charter of Rights and Freedoms, and the obligation to comply with Canadian law.

The other country's nationality law determines whether dual citizenship is permitted from that side. Many countries (including the United Kingdom, the United States, France, Italy, Ireland, Israel, Mexico, and most European Union member states) recognise dual citizenship. Some countries (including China, India, Japan, Saudi Arabia, and Singapore) do not, requiring renunciation of previous citizenship as a condition of acquisition or upon reaching adulthood. Permanent residents of Canada who become Canadian citizens may need to consider how acquisition of Canadian citizenship affects their original nationality.

Dual citizenship can complicate consular services, military service obligations, taxation, and travel. Canada cannot generally intervene on behalf of a Canadian citizen detained on the territory of their other citizenship, since the host country may not recognise the dual nationality. Dual citizens may face military conscription in the other country (such as Israel's compulsory service or South Korea's military service requirement). The United States taxes its citizens on worldwide income regardless of residence, creating an ongoing federal tax obligation for U.S. citizens who reside in Canada. Federal Bill C-24 of 2014 had introduced provisions allowing revocation of citizenship from dual citizens convicted of certain offences, but these provisions were repealed by Bill C-6 of 2017 (which received Royal Assent on June 19, 2017) restoring the principle that all Canadian citizens are equal.