What the First Digit of Your SIN Number Really Means in Canada

When you receive your Social Insurance Number (SIN) in Canada, it may look like a random set of nine digits — but it’s not!
Your SIN actually contains useful information, and one of the most interesting details is this:

👉 The first digit of your SIN tells you which province or territory issued it.

Whether you’re new to Canada or simply curious about how things work behind the scenes, here’s a clear breakdown.

Why Does the First Digit Matter?

The first digit helps identify where your SIN was originally registered.
Although Canadians can move across the country, your SIN number remains the same for life — so the first digit stays tied to the province or region where it was first issued.

This can be helpful for understanding government data, processing applications, or verifying documentation.

SIN Number Starting Digits by Province / Territory

Here’s what each starting number represents:

1 — Atlantic Provinces

This includes:

Newfoundland & Labrador
Nova Scotia
New Brunswick
Prince Edward Island

2 & 3 — Québec

SINs starting with 2 or 3 were issued in Quebec.
Quebec has a large population and historically needed two ranges.

4 & 5 — Ontario

Ontario also uses two starting digits due to its population size.

6 — Prairie Provinces & Territories

This covers:

Manitoba
Saskatchewan
Alberta
Northwest Territories
Nunavut
Yukon (previously, but now commonly under 7)

7 — British Columbia & Yukon

SINs starting with 7 are most commonly linked to BC and Yukon residents.

9 — Temporary Residents

SINs starting with 9 are issued to people who are not permanent residents or citizens, such as:

Temporary foreign workers
International students
Individuals with time-limited work permits

These SINs have an expiry date tied to the individual’s permit.

Does Your SIN Number Ever Change?

No — once issued, your SIN number stays with you for life, even if you move to a different province.
Only in rare cases of identity theft or legal identity change will Service Canada issue a new number.

Why Is This Good to Know?

Understanding your SIN’s starting digit can help you:

✔ Confirm if a SIN is valid when dealing with paperwork
✔ Understand historical records or credit file origins
✔ Learn a little fun fact about how Canada organizes national data
✔ Educate newcomers on the Canadian system

It’s a small detail that tells a big story about where your Canadian journey began.