Certificate of Sponsorship (CoS)

A digital record generated by a licensed UK employer in the Home Office's Sponsor Management System, confirming a specific job, salary, and worker for the Skilled Worker (or other Worker route) visa. It is not a physical certificate — it's a reference number the worker enters into their visa application, and no Skilled Worker application can be submitted without one. A CoS must generally be used within 3 months of being assigned and is tied to that one role at that one employer; it isn't transferable if the worker changes jobs.