Certificate of Sponsorship explained

A Certificate of Sponsorship is not a physical document. It is a digital record held in the Home Office's sponsorship management system that contains details about the job offer, the employer, and the worker being sponsored. The reference number is used by the applicant when completing their visa application.

There are two types: defined CoS, which are pre-assigned by the Home Office for specific roles or quota-controlled routes, and undefined CoS, which employers assign directly for most Skilled Worker roles. The employer must assign the CoS before the applicant applies for the visa.

The Home Office publishes periodic transparency datasets showing how many Certificates of Sponsorship have been issued by employers. These datasets are used by research tools to build a picture of which companies have historically issued sponsorship and at what scale.

When you see a CoS count on a company profile, it typically reflects matched records from these published datasets. A higher count usually suggests the employer has issued sponsorship repeatedly, which is a useful research signal — though it does not confirm that a specific current vacancy offers sponsorship.

An employer with a track record of issuing CoS certificates is often a stronger target than a company that holds a licence but shows limited CoS activity. The certificate count and recency of sponsorship can help you prioritise your shortlist.

However, the absence of a high CoS count does not necessarily mean a company will not sponsor you. Some valid sponsors are smaller, newer, or operate in niche areas. Always combine CoS research with live vacancy checks and direct outreach to confirm a specific role's sponsorship position.