What tax number does a newcomer need to file a first return?
Bottom line: Use your Social Insurance Number when eligible; if Service Canada cannot issue a SIN, CRA guidance says a temporary tax number may be available in qualifying cases.
What the current CRA rule means
CRA’s 2026 newcomer tax tip lists the SIN as the normal identifier used on the return. Do not invent or reuse an identifier; follow Service Canada and CRA instructions for your immigration and tax situation.
Why newcomers get this wrong
The first Canadian tax year combines several systems that are easy to mix together: immigration status, income-tax residency, benefit eligibility, filing access and foreign-information reporting. A rule that answers one of those questions does not automatically answer the others. For example, income earned before Canadian tax residency may be outside ordinary Canadian taxation but still be requested to calculate income-tested benefits or certain credits.
What to verify before filing
Confirm the date Canadian tax residency actually began, gather Canadian and foreign income records for the relevant periods, and keep documents supporting any cross-border position. If the issue involves a tax treaty, foreign corporation, trust, significant foreign investments or an uncertain residency date, the downside of getting the treatment wrong can be much larger than the cost of professional advice.
Primary CRA source
CRA — Taxes made simple for newcomers →
Related newcomer tax tools
Newcomer First Tax Return Checker →
2026 Newcomer Tax & Benefit Rules Reference →
First Canadian tax return guide →
Tax residency for newcomers →
Tax software in Canada →
This page summarizes public CRA guidance and is not personalized tax advice. Rules and forms can change.