What should I do if I don't remember my SIN number?

If you don't remember your Social Insurance Number (SIN), you can find it on your SIN card, tax documents, or pay stubs if you have previously worked. If you cannot locate it, you can apply for a replacement SIN card or letter from Service Canada by providing proof of identity, such as a birth certificate or passport. You can also contact Service Canada directly for assistance in retrieving your SIN.