How to check Certificate of Sponsorship (CoS) status online? If you have been offered a job in the UK, your employer will need to provide you with a Certificate of Sponsorship (CoS). This document is used to prove that your employer is licensed to sponsor overseas workers and that your job meets the requirements for skilled work. You can check the status of your CoS online using the UK Visas and Immigration website. To do this, you will need to enter your CoS number and your date of birth. If yo