See the guide:
https://www.canada.ca/en/immigratio...onditions-extend-your-stay-canada-worker.html
Offers of Employment from a specific employer for LMIA-exempt foreign workers
If an employer is offering you a specific job, then you need an
Offer of Employment number. In order to obtain this number, the employer must use the
Employer Portal to:
- submit the offer of employment information and
- pay the $230 employer compliance fee or upload proof of their fee exemption
Make sure the employer gives you the
Offer of Employment number before you submit your work permit application. The Offer of Employment number starts with an “A” and is followed by 7 numbers.