The Social Insurance Number (SIN) is a nine-digit
number that you need to work in Canada or to have access to government programs
and benefits.
You can’t file a tax return in Canada without a
Social Insurance Number or an Individual Tax Number (ITN). If you don’t have
either, you will need to contact the CRA to get one. If you are in Canada or
the United States, you can call 1-800-959-8281. If you are somewhere else you
can call 613-940-8495. Here are more ways to contact the CRA:
https://www.canada.ca/en/revenue-agency/corporate/contact-information/telephone-numbers.html
