主题：想过孟事件有内鬼没有？ -- bluestarry

另一种，给工签和允许打工的学生， 以9子开头， 有失效日期。

SINs that begin with a "9" are issued to temporary workers who are neither Canadian citizens nor permanent residents. The use of these SINs is temporary and are valid only until the expiry date indicated on the immigration document authorizing them to work in Canada.

If your SIN begins with a "9", you must update your SIN record to ensure that the expiry date always corresponds with the expiry date on your document from Immigration, Refugees and Citizenship Canada authorizing you to work in Canada. Once your SIN record has been updated, you will receive a SIN with the new expiry date. Your previous SIN (whether it is a paper format or plastic card) is no longer valid and should be destroyed in a secure manner.