Why a SIN Is Needed
A Social Insurance Number (SIN) is a 9-digit number. Service Canada says it is required to work legally in Canada, get paid and pay taxes, access government programs like Employment Insurance and the Canada Pension Plan, and file income taxes.
Immigration, Refugees and Citizenship Canada (IRCC) lists a SIN among the requirements to work on or off campus.
A SIN That Starts With 9
Service Canada says a SIN issued to a temporary resident always starts with 9, and expires on the same date as the work permit, study permit or visitor record. The SIN record has to be kept up to date so that it matches the current permit.
Applying for a SIN
Documents
Service Canada asks for a valid permit from IRCC that authorizes work. A study permit must indicate that the holder “may accept employment” or “may work” in Canada. Email messages from IRCC are not accepted. One secondary document is also needed. It must be valid, show the full legal name and date of birth, and be issued by a Canadian government or be a foreign passport. Examples are a passport or a Canadian driver's licence. A supporting document is needed if a name does not match.
If the Work Conditions Are Missing
IRCC says an eligible student can ask to have work conditions added to the study permit, at no fee, and must request that amendment before applying to Service Canada for a SIN. A permit that says the holder cannot work off campus is different. A student who has changed to a program that may allow off-campus work may be able to apply to change the conditions. IRCC says there is a fee, and the change must be made before applying for a SIN.
How and How Long
Service Canada says there is no fee to apply. An application can be made online, by mail or in person, and online is the fastest option. It gives about 5 business days for online applications and about 20 business days by mail, if everything is complete and all required documents are included.
Starting Work
IRCC says a student can only start working once their study program has started, and lists a SIN among the requirements to work on or off campus. Service Canada's page for temporary residents says a person can start working as soon as they apply for a SIN, without waiting for the number.
When a Permit Changes
Service Canada says a temporary resident must apply for or update their SIN record if they are legally authorized to work and will be working, need proof or confirmation of their SIN, receive a new permit with a new expiration date, have a change in immigration status or legal name, or need to correct an error.
If a SIN expires but the person applied to extend their permit and is on maintained status, Service Canada says they can continue working with the expired SIN until IRCC makes a decision. IRCC says status is maintained only if the application was submitted before the status expired and the person remains in Canada, and that it ends when they leave Canada. Once IRCC authorizes them to continue working, they must apply to Service Canada with the new immigration document to update the expiry date. The old SIN document is no longer valid and is to be destroyed.
Protecting a SIN
Service Canada says a SIN is confidential and that a person is responsible for protecting it. It says to provide a SIN only when the law requires it, and lists employment, financial accounts and government services as those situations. For employment, it says the SIN is only required after hiring and upon earning income.
It also says not to keep a confirmation of SIN letter or a SIN card in a wallet or bag, and to keep documents containing a SIN in a locked cabinet or safe, or on password-protected devices.