Social Insurance Number (SIN)
Your Social Insurance Number (SIN) is a unique 9-digit number issued by Service Canada. It identifies you for income tax purposes under section 237 of the Income Tax Act and is also used for certain federal programs.
Your SIN is confidential, but you must provide it to anyone who prepares your information slips (such as a T3, T4, or T5 slip), including your employer, trustee, bank, or investment company. You must also give it to the Canada Revenue Agency when requesting personal tax information.
If you do not provide your SIN when required, you may have to pay a $100 penalty.
Check your slips every year. If your SIN is missing or incorrect, tell the slip preparer.
For more information or to apply for a SIN, visit Social Insurance Number (Service Canada).
If you do not have a SIN
If you applied for a SIN but will not receive it before the filing due date, or if you are not eligible to receive a SIN, file your return using your temporary tax number (TTN) or individual tax number (ITN), whichever applies.
If you do not have a SIN, a TTN or an ITN, file a paper return without entering a number. Include a cover letter explaining why you do not have a SIN or cannot get one, and attach a certified copy of your proof of identity (such as a passport, driver's license, or birth certificate). For more information, contact the CRA.
Completing your tax return
Enter your SIN in Step 1 – Identification and other information of your Income Tax and Benefit Return.