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What is a Social Insurance Number (SIN)? Do I need one?

The Social Insurance Number (SIN) is a unique number that you use to identify yourself. It is a 9-digit number. You need this number to use some government programs. You need this number to work in Canada.

You need a Social Insurance Number (SIN) to work in Canada. This number identifies people who:

Earn money through work and investments
Pay taxes
Contribute to pension plans
Use government services

It's a good idea to apply for your SIN as soon as you can. That way, you will have it when you need it.

An employer cannot pay you if you do not have a SIN. The law in Canada says that your employer has to ask you for your SIN within 3 days after you start a job.

Filing Income Tax

In most cases you need a SIN to file your income taxes. In some cases, you cannot get a SIN because you are not eligible. This is the case for some temporary residents. If you cannot get a SIN, you can use an Individual Tax Number (ITN) or Temporary Taxation Number (TTN) to file taxes, instead of a SIN.

When You Do Not Need a SIN

You do not always have to provide your SIN, even if someone asks for it. For example, banks often ask for a SIN, but you can open a bank account without having a SIN.

For more information about when you need to provide your SIN and when you don't, go to Who should I show my SIN to?

Do Children Need a SIN?

Children do not need a SIN unless they will earn money from a job or from an investment in their name. For example, if your child has a Registered Education Savings Plan (RESP), your child might need a SIN.

However, if your child is eligible for a SIN, you can apply for one so that it will be ready when they need it.

If your baby is born in Canada, you can apply online for a birth certificate and Social Insurance Number using the Newborn Registration Service. You can use this service until your child is 1 year old. After your child is 1 year old, you can apply for a SIN from Service Canada.

For More Information

Social Insurance Number - Answers to questions about the Social Insurance Number. From Service Canada.
Protecting Your SIN: A Shared Responsibility - A fact sheet on how to protect your SIN from inappropriate use, fraud or theft.
Social Insurance Number Fact Sheet - Information about when you need to show your SIN and when you don't. From the Office of the Privacy Commissioner of Canada.