If you can't locate your Social Identification Number, or SIN, after looking in the usual places, including past income tax returns, it's time to turn to Canada's Employment and Social Development Department. You can obtain your SIN by requesting a Confirmation of SIN letter from ESDA.
In Person Request
The Employment and Social Development Department provides a list of local offices online. Search by zip code, city, province or territory. There isn't a fee for SIN confirmation requests. However, you must provide proof of identity when you visit your local office and it must be an original document. It can be in French or English. Acceptable proof includes a marriage certificate, divorce decree, court-issued name change certificate and adoption order.
SIN Application
If you are unable to visit a local office, you can request a copy of your SIN by mail. Complete an Application for a Social Insurance Number. The form is available online from ESDC's website. You can also call ESDC at (506) 548-7961 and have it mailed to you. Although the form can be completed online, it can't be submitted that way. When finished, you must print the completed form and mail it in. Check the box labeled "Confirmation of SIN" to inform the ESDA staff member reviewing the form that it is a request for your existing SIN rather than a new number. The application will ask for such information as your name, sex, date of birth and parents' names. Sign and date the application when finished. Send completed application and identification document to the following address: Service Canada, Social Insurance Registration Office, P.O. Box 7000, Bathurst, NB E2A 4T1, Canada.
Status Update
Generally, ESDA will send confirmation of your SIN within 20 business days from the date it receives your application. If more time has passed, check the status of your request by calling ESDA at (800) 206-7218 weekdays between 8:30 a.m. and 4:30 p.m. Canadian Local Time. Select Option 3. If outside Canada, call (506) 548-7961 weekdays between 8 a.m. and 8:30 p.m. Atlantic Standard Time. Your identity document will be returned to you after your application is processed.
Lost or Stolen SIN
If your SIN was lost or stolen, ESDA will not issue you a new one. It will do so only if your SIN has been fraudulently used and you can prove it. For example, if you didn't work for six months due to a disability, but someone used your SIN during the same time to work at a location miles away, this is evidence someone else is using your SIN and you can get a new number. Another indicator is if you receive a notice of undeclared earnings from the Canada Revenue Agency.