Social insurance number (SIN)
Your SIN is the number that identifies you for income tax purposes under section 237 of the Income Tax Act and is used for certain federal programs. You must give it to anyone who prepares information slips (such as T3, T4, or T5 slips) for you. Each time you do not give it when you are supposed to, you may have to pay a $100 penalty. Check your slips. If your SIN is missing or is incorrect, inform the slip preparer. You must also give it to the CRA when you ask the CRA for personal tax information.
For more information or to get an application for a SIN, contact Service Canada.
Completing your tax return
Enter your SIN in the "Step 1 – Identification and other information" section of your income tax and benefit return.
Forms and publications
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