If you work or live on both sides of the US-Canada border, you may need to understand two different tax identification numbers: Canada's Social Insurance Number (SIN) and the US Individual Taxpayer Identification Number (ITIN). These serve different purposes, and many cross-border individuals need both.
What Is a SIN (Social Insurance Number)?
A Social Insurance Number is a nine-digit identifier issued by the Government of Canada through Service Canada. It is used to:
- Work legally in Canada and receive employment income
- File Canadian income tax returns with the CRA
- Access government benefits (EI, CPP, OAS, GST/HST Credit)
- Open registered accounts (RRSP, TFSA, RESP)
- Have interest and investment income reported to CRA
A SIN is issued to Canadian citizens, permanent residents, and temporary residents (work/study permit holders). It is not a national ID card — it is strictly for tax and employment purposes. Learn more about the SIN application process.
What Is an ITIN (Individual Taxpayer Identification Number)?
An ITIN is a nine-digit tax processing number issued by the US Internal Revenue Service (IRS) to individuals who need a US taxpayer identification number but are not eligible for a Social Security Number (SSN). It is formatted as 9XX-XX-XXXX, starting with a 9.
An ITIN is used to:
- File US federal tax returns if you have US-sourced income
- Claim tax treaty benefits between the US and Canada
- Report US rental income, dividends, or capital gains
- Open certain US bank accounts from outside the US
An ITIN does not authorize you to work in the US, does not provide Social Security benefits, and does not prove immigration status.
| Feature | SIN (Canada) | ITIN (USA) |
|---|---|---|
| Issuing Authority | Service Canada | IRS (Internal Revenue Service) |
| Format | 9 digits (e.g., 123 456 789) | 9XX-XX-XXXX (always starts with 9) |
| Purpose | Work authorization + tax ID | Tax ID only (no work authorization) |
| Eligibility | Citizens, PRs, work/study permit holders | Non-citizens without SSN who have US tax obligations |
| Expires? | No (permanent SINs); temp SINs match permit | Yes — every 3 years if not used; some series expire earlier |
| Work Authorization | Yes — required to legally work in Canada | No — does not authorize US employment |
| Government Benefits | Yes — EI, CPP, OAS, GST/HST Credit | No — does not provide US benefits |
Who Needs Both a SIN and an ITIN?
Several groups of people may need both numbers:
- Canadians with US rental property: You need an ITIN to file US tax returns for rental income from US property
- US citizens living in Canada: You keep your SSN (not an ITIN) for US filing, but need a SIN for Canadian employment and taxes
- Canadians employed by a US company: May need an ITIN to receive compensation under a US-Canada tax treaty
- Snowbirds with US investment income: Dividends and capital gains from US accounts may require an ITIN
- Canadian contractors doing US work: US clients may withhold tax unless you provide an ITIN or W-8BEN form
US Citizens Moving to Canada — SSN vs ITIN
If you are a US citizen moving to Canada, you do not need an ITIN — you already have a Social Security Number (SSN). US citizens living abroad must still file US tax returns every year, reporting worldwide income to the IRS. You will also need a Canadian SIN for working and paying taxes in Canada.
This creates a dual-filing obligation. The US-Canada Tax Treaty prevents most double taxation, but the filing obligation remains. See our US-Canada cross-border banking and tax guide for full details.
How to Apply for an ITIN From Canada
Canadians who need an ITIN can apply by:
- Completing IRS Form W-7 (Application for IRS Individual Taxpayer Identification Number)
- Attaching a completed US tax return (1040-NR) or qualifying documentation showing your tax need
- Providing original identity documents or certified copies (passport is preferred)
- Submitting to the IRS by mail or through an IRS Certified Acceptance Agent (CAA)
Processing time: 7–11 weeks under normal circumstances, longer during peak filing season. Applying through a CAA in Canada avoids sending original documents to the IRS.
ITIN Renewal Requirements
ITINs expire if not used on a US federal tax return for three consecutive years. Additionally, ITINs with certain middle digits were assigned expiry dates under IRS rules and must be renewed even if used. Check the IRS website or consult a cross-border tax professional to verify your ITIN status.
Canadian Banking Without a SIN
While a SIN is not legally required to open a bank account, you will need one for tax reporting purposes. If you are waiting for your SIN, KOHO offers a full-featured bank account that you can open with just a passport — no SIN required at signup. You can add your SIN later. See our newcomer banking guide.