If you’re applying for a Skilled Worker visa, you can’t apply without a Certificate of Sponsorship (CoS). Despite the name it isn’t a paper certificate — it’s an electronic record your employer creates. Here’s exactly what a CoS is, the two types, what it costs and how the process works in 2026.
What is a Certificate of Sponsorship?
A CoS is an electronic record with a unique reference number that a licensed UK sponsor (your employer) assigns to you through the Home Office Sponsor Management System. It confirms the job meets the visa rules and records the details — job title and SOC code, salary, start date and duties. You then enter its reference number when you apply for your visa.
Defined vs undefined CoS
- Defined CoS — for Skilled Worker applications made from outside the UK. The employer requests it individually and the Home Office usually approves it within 1 working day.
- Undefined CoS — for applications made from inside the UK (switching or extending) and certain other routes. These come from the sponsor’s annual allocation and are available immediately.
For a deeper comparison, see our guide to defined vs undefined CoS.
How much does a CoS cost?
The employer pays £525 per Worker CoS (the same whether defined or undefined). On top of that, sponsors usually pay the Immigration Skills Charge (£1,000 per year for large sponsors, £364 for small/charitable ones) and hold a sponsor licence. The worker separately pays the visa fee, the Immigration Health Surcharge and so on.
How long is it valid?
A CoS is valid for 3 months from assignment — you must submit your visa application within that window, or the employer may need to assign a new one. The start date on the CoS also can’t be more than 3 months ahead.
How the process works
- The employer holds (or applies for) a sponsor licence.
- They request a defined CoS (overseas hire) or use an undefined CoS from their allocation (in-UK hire).
- They assign the CoS to you, paying the £525 fee, and give you the reference number.
- You apply for your Skilled Worker visa within 3 months, entering the CoS number and meeting the salary rules (see the salary thresholds & shortage lists).
Frequently asked questions
What is a Certificate of Sponsorship (CoS)?
An electronic record with a unique reference number that a licensed UK employer assigns to a worker, needed to apply for a Skilled Worker or other sponsored visa.
How much does a CoS cost?
£525 per Worker CoS, paid by the employer, whether it is a defined or undefined certificate.
What is the difference between a defined and undefined CoS?
A defined CoS is for Skilled Worker applications from outside the UK; an undefined CoS is for in-UK applications such as switching or extending.
How long is a Certificate of Sponsorship valid?
3 months — you must submit your visa application within 3 months of the CoS being assigned.
How long does it take to get a CoS?
A defined CoS is usually processed within 1 working day; an undefined CoS is allocated immediately from the sponsor’s annual quota.
What does the worker do with the CoS?
Enter its unique reference number when applying for the Skilled Worker visa, within the 3-month validity.
