Social insurance number

[3] Unless an organization can demonstrate that the reason it is requesting an individual's SIN is specifically permitted by law, or that no alternative identifiers would suffice to complete the transaction, it cannot deny or refuse a product or service on the grounds of a refusal to provide a SIN.

Examples of organizations that legitimately require a SIN include employers, financial institutions that provide interest on deposits, and federal government agencies.

Giving a SIN when applying for consumer credit, such as buying a car or electronics, or allowing it to be used as a general purpose identification number, such as by a cable company, is strongly discouraged.

Military identification, including ID cards and identity discs were marked with the SIN during this period.

Social Insurance Numbers can be validated through a simple check digit process called the Luhn algorithm.

A social insurance number card. Note the date of expiration, which implies that the holder is neither a permanent resident nor a Canadian citizen.