As an employer, you have to ask your employees for their social insurance number (SIN) within three days of when they start to work for you, and record their number. If an employee does not give you his or her SIN, you must be able to show that you made a reasonable effort to get it.
If you do not make a reasonable effort to get your employee's SIN, you may have to pay a penalty of $100 for each number you don't try to get.
Employees who are in pensionable or insurable employment also have to give you their SIN within three days of starting to work for you and they can be penalized $100 for each time they don’t provide it.
Under the Department of Employment and Social Development Act, an employee who does not have a SIN when they start working for you has to apply for one and give it to you within three days after they receive it. As an employer, you must inform Service Canada within six days of your employee starting to work for you that this individual did not give you his or her SIN. If your employees need a SIN, refer them to their Service Canada Office.