Claiming Canadian Citizenship Through a Parent or Grandparent: What Changes on Your Taxes, and What Doesn't

Canadian citizenship by descent is an immigration windfall that people expect to be a tax event, and the first thing to say is that it mostly isn't. The status: a person born outside Canada to a parent who was a Canadian citizen at the time of the birth is generally a Canadian citizen by descent, subject to the first-generation limit that restricted citizenship to the first generation born abroad from 2009 — a limit the Ontario Superior Court found unconstitutional in Bjorkquist (2023) and that Parliament has now replaced: Bill C-3 (royal assent November 20, 2025; in force December 15, 2025) repealed the first-generation limit, so a person born abroad before December 15, 2025 who was excluded only by that limit is a citizen automatically, and for a child born or adopted abroad on or after December 15, 2025 a foreign-born Canadian parent transmits citizenship only if that parent had at least 1,095 days (three years) of cumulative physical presence in Canada before the birth or adoption — the substantial-connection test now in force, and the rule anyone claiming through a grandparent works from; the certificate of citizenship confirms the status, and the person has been a citizen since birth — the certificate declares, it does not confer. What does not change: Canada taxes on the basis of residence, not citizenship — a Canadian citizen living in the United States who has never lived in Canada is a non-resident of Canada with no Canadian filing obligation and no Canadian tax on non-Canadian income, exactly as before the certificate; there is no Canadian equivalent of the US citizenship-based taxation, no Canadian FBAR, no worldwide return, and no exit tax on renouncing (Canada's departure tax is a residence event, not a citizenship one); and the US side is unchanged too — the American who becomes a dual citizen still files a 1040 on worldwide income as a US citizen wherever they live. What does change, in the tax rules that key off citizenship. The treaty's collection article: Article XXVI A's carve-out — each country need not collect the other's tax claims against a person who was its citizen when the claim arose — now protects the new Canadian citizen's Canadian assets from CRA-assisted collection of US tax debts arising after the citizenship date (and, since citizenship by descent runs from birth, arguably for claims arising at any time — a position the collection guide covers); the treaty's tie-breaker: nationality is the fourth test, after permanent home, center of vital interests, and habitual abode — a dual citizen who reaches it (rare) is resolved by competent authority agreement rather than by nationality; the US estate and gift rules: the marital deduction's non-citizen-spouse limitation turns on the recipient spouse's US citizenship, which Canadian citizenship by descent doesn't affect (the QDOT guide), and the covered-expatriate rules include an exception for certain dual citizens at birth who renounce US citizenship — an individual who became at birth a citizen of both the US and another country, continues to be a citizen of the other country and taxed as its resident, and has not been a US resident for more than ten of the fifteen years before expatriation is exempt from the net worth and tax liability tests (but not the certification test), which for a US-born person with Canadian citizenship by descent who later moves to Canada and considers renouncing is a materially easier exit — one of the two places where the certificate genuinely changes a tax result; and the Canadian side of a later move: a citizen entering Canada to live is a newcomer for tax purposes on the same rules as anyone (residency by ties, the arrival cost basis, the newcomer guides) — citizenship makes the immigration trivial and the tax identical. The doors the citizenship opens, which are the reasons people claim it: the right to live and work in Canada without immigration process (and to pass citizenship to children, subject to the generation rules); access to Canadian post-secondary tuition at domestic rates for the citizen's children who establish residence; the Canadian passport; and — for the American considering the retire-in-which-country decision the comparison guide models — a real option to become a Canadian resident, with the tax consequences that follow from residence, not from the certificate. The interaction with US immigration and tax for a Canadian-citizen American living in the US: none — dual citizenship is permitted by both countries, the US does not require a choice, and the American's US tax life continues unchanged; for a Canadian-citizen American who later moves to Canada: the American-in-Canada apparatus (the 1040, FBAR, 8938, PFIC avoidance) applies exactly as to any US citizen resident in Canada, with the citizenship making the residency easy and the tax no different. The one administrative item: the certificate application asks for the parent's Canadian documentation and the applicant's birth records — no tax filings, no Canadian tax number, and no CRA involvement — and the applicant should not, on receiving the certificate, register with the CRA, file a Canadian return, or apply for a social insurance number unless and until they become a Canadian resident or earn Canadian-source income, because a citizen with no Canadian nexus has no Canadian tax presence to create.

Key takeaways

• Canada taxes residence, not citizenship: a new Canadian citizen living in the US owes Canada nothing new — no return, no worldwide reporting, no exit tax on the Canadian side ever.
• The US side is unchanged: the dual citizen files a 1040 on worldwide income as before, wherever they live.
• Where citizenship changes a tax result: the treaty's collection carve-out (Canadian assets shielded from CRA-assisted collection of US claims), and the covered-expatriate exception for dual citizens at birth who later renounce US citizenship from Canada (exempt from the net worth and tax liability tests).
• Where it doesn't: the tie-breaker's nationality test is rarely reached; the marital deduction's non-citizen-spouse rule keys off US citizenship only; a later move to Canada runs the ordinary newcomer rules.
• The doors: living and working in Canada without immigration process, passing citizenship to children (generation rules), domestic tuition, the passport — and a real retire-in-Canada option, whose tax consequences flow from residence.
• Don't create a Canadian tax presence with the certificate: no CRA registration, no return, no SIN until residence or Canadian-source income exists.

The new dual citizen's tax checklist

Nothing to file in Canada while non-resident. The 1040 continues unchanged. Note the collection-carve-out protection and the dual-citizen-at-birth expatriation exception in the estate and exit planning file, because they change future decisions. If a move to Canada is contemplated: the newcomer and American-in-Canada guides, with the citizenship making only the immigration step easier. If children are claiming through you: the Bill C-3 rules — automatic for those born abroad before December 15, 2025, and the 1,095-day substantial-connection test for any born on or after it. A checklist whose main entry is "no change" — and whose two real entries are worth knowing about.

Worked example

A Denver physician, born in Colorado to a Toronto-born mother, obtains her certificate of Canadian citizenship by descent. Tax consequences this year: none — she remains a US citizen filing a 1040, a non-resident of Canada with no Canadian filing, and her Canadian citizenship generates no Canadian tax presence; she does not apply for a SIN or contact the CRA. What it changes in her file: the estate and exit planning note now records that she is a dual citizen at birth — if she ever moves to Canada and later renounces US citizenship, the covered-expatriate exception exempts her from the net worth and tax liability tests (she would still need the five-year compliance certification), a materially cheaper exit than her US$3 million net worth would otherwise face; and the collection note records the treaty carve-out's protection of any future Canadian assets from CRA-assisted collection of US claims. Her children: US citizens by birth, and Canadian citizens by descent through her under the Bill C-3 rules — automatically if they were born abroad before December 15, 2025, and, for any born on or after that date, only if she has at least 1,095 days of physical presence in Canada before the birth (the substantial-connection test). Five years later she takes a position at a Vancouver hospital: the immigration step is a border crossing with a passport; the tax step is the full American-in-Canada engagement — the newcomer rules, the arrival basis, the 1040 with foreign tax credits, FBAR and 8938, no TFSA, PFIC avoidance — identical to what any US citizen moving to Canada would face, and unaffected by the certificate in her drawer.

Official sources

Immigration, Refugees and Citizenship Canada explains that under the 2025 changes to the Citizenship Act, "people born outside Canada in the second generation (or later) may be Canadian if their parent was also born or adopted outside Canada to a Canadian citizen (meaning the grandparent was Canadian), and that same parent spent at least 1,095 days in Canada before the birth." — Government of Canada, Changes to citizenship rules in 2025, https://www.canada.ca/en/immigration-refugees-citizenship/services/canadian-citizenship/act-changes/rules-2025.html

"No assistance shall be provided under this Article for a revenue claim in respect of a taxpayer to the extent that the taxpayer can demonstrate that ... where the taxpayer is an individual, the revenue claim relates ... to a taxable period in which the taxpayer was a citizen of the requested State." — Canada-United States Tax Convention, Article XXVI A(8), https://www.canada.ca/en/department-finance/programs/tax-policy/tax-treaties/country/united-states-america-convention-consolidated-1980-1983-1984-1995-1997-2007.html

Practitioner note

Citizenship by descent is an immigration windfall and a tax non-event, and our first job is to stop the new dual citizen from creating a Canadian tax presence they don't have — no SIN, no CRA, no return while non-resident. Our second job is to record the two places the certificate genuinely changes a future result: the treaty's collection carve-out, and the dual-citizen-at-birth exception that makes a later renunciation from Canada far cheaper — both entries in the planning file that pay off years later, not this April.

See also: Browse every cross-border tax topic guide, organized by situation.

Next step

Fairlight prepares the citizenship-by-descent review — confirmation of no current Canadian tax presence, planning-file entries for the treaty collection carve-out and the dual-citizen expatriation exception, generation-rule flags for children, and the newcomer engagement if a move to Canada follows. See cross-border pricing or book a call.