What Is a Social Insurance Number (SIN) & Why Is It Important?

From 2023 to 2024, 1.7 million first-time Social Insurance Numbers (SINs) were issued in Canada—highlighting the importance of this unique number and the key role it plays in the Canadian workforce.

A Social Insurance Number (SIN) is essential for employees to be able to work in Canada. It also enables workers to access various government programs and benefits. As an employer running a Canadian business, it’s your responsibility to protect your employees' personal information and put measures into place to detect and prevent SIN fraud.

Failing to uphold your duties in relation to employee SINs can result in fines, penalties and other forms of legal liabilities. Read on to learn everything you need to know about SINs as an HR professional.

What is a Social Insurance Number?

A Social Insurance Number (SIN) is a 9-digit number that employees must have to work and receive pay in Canada. It grants them access to government programs and benefits such as Employment Insurance and the Canada Pension Plan.

SINs are used by the government to track an individual's earnings, as well as their contributions to pension and benefit plans. It’s also used to process income tax returns and other federal programs.

Employee Social Insurance Numbers are confidential and once provided to employers, they must be protected from misuse. A SIN is your unique identifier for various federal programs and unauthorized use can lead to breaches of privacy, identity theft and financial loss.

Who needs a SIN?

You need a SIN to work in Canada and receive benefits and services from government programs if you’re a:

• Canadian citizen
• permanent resident
• temporary resident

Children aged 12 years or older may apply for a SIN. However, for children below the age of majority in their province, parents, legal guardians or legal representatives can apply for them. They can also apply for any adults in their care.

Those who aren’t eligible for a SIN can apply for an Individual Tax Number (ITN) for tax purposes. It’s also worth noting that international students are allocated a SIN that begins with the number ‘9,’ so employers can identify them as temporary residents.

What do I need to do with a SIN as an employer?

Employers in Canada are obligated to handle employees’ SINs in accordance with federal regulations. If you’re an employer or part of HR, here are a few things you should bear in mind:

Request your new employee’s SIN within three days

You’ll need to request any new employee's SIN within three days after their employment starts with your company. Make sure you are able to correctly identify your new worker before finalizing their employment documents.

Service Canada issues SINs to employees. They can come in a paper format (Confirmation of SIN letter) or digitally if the employee registers for a My Service Canada Account (MSCA).

Tell employees who don’t have a SIN to apply for one immediately

If a new employee doesn’t have a SIN, but has confirmed that they’re eligible to work in Canada, instruct them to apply for one straight away. Please note, the employee can still work in the interim period before getting their SIN through insurable employment.

Advise employees that they can apply for a SIN for free. They can also update or obtain a SIN confirmation online, plus upload their digital documents securely. Additionally, if they’re eligible, they can view and print their SIN on MSCA once their application has been processed.

Employees can also apply for their SIN in person at a Service Canada office or by mail.

Check that any employees with SINs starting with a 9 are authorized to work

You must confirm that all employees who have a SIN that starts with a "9" are authorized to work in Canada. You should also ensure their immigration document hasn’t expired.

This type of SIN issued to temporary workers who aren’t Canadian citizens or permanent residents. They’re valid until the expiry date provided on the immigration document that authorizes them to work in Canada.

Employers should also request to see the employee's existing immigration document to verify that it hasn’t expired. This could be a work permit or study permit, for example. If the immigration document has expired, advise them to contact Immigration, Refugees and Citizenship Canada (IRCC) to obtain a valid document and issue it to Service Canada for a new expiry date to be entered into their SIN record.

Keep your employees’ details safe

It’s essential that you protect your employees' SIN to prevent identity theft, fraud, and unauthorized access to personal information. Always ensure all personal information is stored in a secure area or on an encrypted computer system, allowing only authorized individuals to have access.

If you think an employee's SIN has been stolen or used inappropriately, take the following measures immediately:

• Determine the extent of the breach.
• Inform the employee(s).
• Contact Service Canada at 1-866-274-6627.
• Get in touch with Equifax: 1-800-465-7166 and TransUnion: 1-800-663-9980. Or for residents of Québec, call 1-877-713-3393.
• Contact the police if there’s been any criminal activity.

Contact Service Canada if you suspect fraud

If you suspect an employee’s SIN has been used fraudulently, you need to inform Service Canada as soon as possible at 1-866-274-6627. You’ll need to provide your business number provided by Canada Revenue Agency, as well as any appropriate identification.

Take a look at the Personal Information Protection and Electronic Documents Act to find out the rules regarding how private-sector organizations are permitted to collect, use or disclose personal information. And for further information, head to the Office of the Privacy Commissioner of Canada.

SIN number FAQs

Is SIN the same as SSN?

No, a Social Insurance Number (SIN) is not the same as a Social Security Number (SSN). A SIN is used to enable work and grant access to government programs in Canada, while a SSN is used for these same purposes in the US. Please note, employees cannot use a SIN for US tax purposes, and an SSN is not valid for use in Canada.

How to apply for a Social Insurance Number

Employees can apply for a Social Insurance Number online. They must have all the necessary documents to hand, which can include a birth certificate, certificate of Canadian Citizenship, passport or work permit—depending on their status in Canada and how they’re applying. Workers can also apply for their SIN in person at a Service Canada Centre or by mail.

How long is a SIN valid?

For Canadian citizens, a SIN is valid for life. However, for temporary residents whose SIN begins with ‘9’, the SIN is linked to the expiry date on their Immigration, Refugees and Citizenship Canada (IRCC) document—this can be their work or study permit.

To update this expiry date, the employee must apply to renew their immigration status and apply to update their SIN so that the expiry dates match.