SIN number format: what a valid SIN looks like.

The SIN format in four rules

• Nine digits. No letters. A capital O is not a zero and a lowercase l is not a one, which is the most common copy-and-paste slip.
• Grouping is presentation. It is usually shown as three groups of three, with spaces or hyphens. Forms should accept either, and the stored value should be the nine digits only.
• Do not read a province into the first digit. The Service Canada pages we reviewed describe one meaning only: a SIN that starts with 9 belongs to a temporary resident and expires with their immigration documents.
• The ninth digit is a check digit. It is computed from the first eight with the Luhn scheme, so a single mistyped digit is caught. See how to validate a SIN number.

SIN number first digit and province

Older third-party tables map first digits to regions where a SIN was originally issued. Service Canada does not show such a table in the pages we reviewed, so we do not reproduce one here. Never guess where someone lives, or whether they are a citizen, from the digit. The one reliable reading is the leading 9.

Common SIN formatting mistakes

• Eight or ten digits after a dropped or doubled keystroke.
• A leading zero lost when a spreadsheet stores the SIN as a number. Store it as text. A SIN written 046454286 becomes 46454286, which is only eight digits.
• Dots, slashes or a stray letter pasted in from a scan.

Shape is not validity

A number with the right shape can still fail the checksum, and a number that passes the checksum can still be one nobody holds. For the full check use the SIN validator. To compare a SIN with a business or tax number, see SIN vs BN vs ITN.

Frequently asked questions

How many digits is a SIN number?

Nine. Spaces or hyphens between groups of three are only formatting.

What is the format of a Canadian SIN?

Nine digits, usually written as three groups of three such as 046 454 286, with the ninth digit acting as a check digit.

What does the first digit of a SIN mean?

Per Service Canada, a SIN that starts with 9 is a temporary resident’s SIN and expires with their immigration documents. The Service Canada pages we reviewed describe no other meaning, so do not infer a province or status from other digits.

Does the SIN first digit show which province issued it?

Do not rely on it. Old third-party tables link digits to regions, but Service Canada does not present that on its current pages, and people move.

Why does my spreadsheet show only eight digits?

A SIN starting with 0 loses its leading zero when treated as a number. Format the column as text.

Sources (retrieved October 2026): Service Canada: Social Insurance Number; Service Canada: SIN for temporary residents; ISO/IEC 7812-1 (Luhn check digit). TNAADO is not affiliated with the Government of Canada; this page is general information, not legal or immigration advice.