Certificate of Sponsorship: What It Is and Why It Matters

Introduction
If you are applying for a UK Skilled Worker Visa, you cannot do so without a Certificate of Sponsorship (CoS). This is an electronic document issued by a licensed employer that proves you have been offered an eligible job in the UK. Understanding what a CoS is, how it works, and why it matters is essential for a smooth visa application.

What Is a Certificate of Sponsorship?

A Certificate of Sponsorship is not a paper certificate but a unique reference number issued by an employer who holds a sponsor licence. It links your job offer to your visa application and confirms that your role is genuine, eligible, and meets the Skilled Worker Visa requirements.

Types of Certificates of Sponsorship

There are two main types of CoS:

1. Defined CoS

   • For applicants applying from outside the UK.

   • Issued for new hires entering the UK on a Skilled Worker Visa.

2. Undefined CoS

   • For applicants already inside the UK.

   • Used for visa extensions, job changes, or switching employers.

Why the CoS Matters

• Proof of eligibility: Confirms your job is eligible for Skilled Worker sponsorship.

• Salary check: Confirms that your salary meets the correct threshold (currently £41,700 or the going rate, whichever is higher from July 2025).

• Employer responsibility: Shows that your employer is approved and authorised to hire overseas workers.

• Visa application link: You cannot apply for the Skilled Worker Visa without a valid CoS reference number.

How Employers Issue a CoS

Only employers with a valid sponsor licence can assign a CoS. The process usually involves:

1. The employer applying for and receiving permission to sponsor the role.

2. Assigning a CoS to the candidate via the Home Office’s online Sponsor Management System (SMS).

3. Providing the candidate with the CoS reference number to use in their visa application.

Common Mistakes to Avoid

• Applying for a Skilled Worker Visa without checking your CoS reference number.

• Confusing a job offer letter with a Certificate of Sponsorship.

• Accepting a CoS from an employer who is not on the list of licensed sponsors.

Conclusion

The Certificate of Sponsorship is at the heart of the Skilled Worker Visa process. Without it, applicants cannot move forward with their visa applications. By ensuring that your employer is licensed and your CoS is valid, you can take a confident step towards starting your career in the UK.