What Is a Certificate of Sponsorship in the UK Immigration System?
⭐ In the UK immigration system, the CoS acts as the bridge between the employer, the worker, and the Home Office. Without it, you cannot apply for most work visas.
If you are applying for a UK work visa, or sponsoring someone who is, you will quickly come across the term Certificate of Sponsorship (CoS). Despite its official name, a CoS is not an actual physical certificate. It is a digital record issued by a UK employer licenced by the Home Office to confirm that they are offering a genuine job to a migrant worker that meets immigration requirements.
🌍 How the Certificate of Sponsorship Works
Only employers with a valid sponsor licence can issue a CoS. They do this using the Home Office’s online Sponsorship Management System (SMS).
Each Certificate of Sponsorship includes important details such as:
Job title and job description
Standard Occupational Classification (SOC) code
Salary and working hours
Start date and expected duration
Worker’s personal and passport details
Confirmation that the role meets Skilled Worker visa rules
This makes the CoS a core part of the Skilled Worker visa, Health and Care Worker visa, Temporary Worker visa, and several other work routes.
🧩 Types of Certificate of Sponsorship
There are two key categories under the UK immigration system:
Defined CoS: Used when a Skilled Worker visa applicant is applying from outside the UK (with some exceptions). Sponsors must request each Defined CoS from the Home Office before assigning it, usually processed within one working day. We can help you with requesting and assigning CoS.
Undefined CoS: Used for Skilled Worker visa applicants applying from inside the UK, and all other sponsored work routes (including Senior or Specialist Worker and Temporary Worker visas). Employers receive an annual allocation for Undefined CoS which can be renewed or increased. We can help you with increasing or renewing your annual allocation.
✅ Why the CoS Matters
A valid Certificate of Sponsorship is essential for a UK work visa application. It confirms that:
The job offer is genuine and meets the salary/skill thresholds
The employer is licensed to sponsor workers
The worker has been matched to an eligible role
Immigration rules are being correctly followed
For workers, the CoS is the first step toward securing a UK work visa. For employers, it is a key part of sponsor licence compliance and ongoing responsibilities.
❓ Frequently Asked Questions (FAQs)
Is the Certificate of Sponsorship a physical document? No; it is a digital record with an electronic reference number included in your visa application.
How long is a CoS valid for? Each Certificate of Sponsorship is valid for three months from the date it is assigned, which means it must be used in a valid visa application within that period.
Who pays for the CoS? The employer must pay the CoS assignment fee and, where applicable, the Immigration Skills Charge (ISC).
Does a CoS guarantee a visa? No; the worker must still meet all other visa requirements (e.g., English language, salary level, etc). We can assist with your visa application to ensure you meet all requirements.
Can a CoS be reused after a visa refusal? Generally no; a new CoS is usually required (with some exceptions).
How long does a CoS take to be approved? Defined CoS are approved within one working day, but there may be delays. Undefined CoS can take up to 18 weeks but there may be priority services available.
Need help with a sponsor licence, CoS matters, or visa support?