What is a Certificate of Sponsorship (CoS)?
A Certificate of Sponsorship is an electronic record that UK sponsors assign to overseas workers to confirm a genuine job offer. It is essential for the worker's visa application and forms the basis of your sponsorship relationship.
Part of the Compliance Guide
This article supports ourComplete Sponsor Licence Compliance Guide.
What is a CoS?
A Certificate of Sponsorship is not a physical document. It is an electronic record created by sponsors through the Sponsor Management System (SMS). Each CoS has a unique reference number that workers use when applying for their visa.
The CoS contains details about the job offer—role, salary, location, and start date. This information must be accurate because the Home Office uses it to assess the visa application, and any discrepancies between the CoS and actual employment can lead to compliance failures.
Types of Certificate of Sponsorship
Defined Certificate of Sponsorship
For workers applying from outside the UK. Requires Home Office approval before assignment. Valid for 3 months from assignment.
Use case: New hires applying for entry clearance from abroad
Undefined Certificate of Sponsorship
For workers already in the UK who are switching visa categories or extending. Drawn from your annual allocation. Valid for 3 months.
Use case: Hiring someone already in UK on different visa, or extending current worker
What Information Does a CoS Contain?
CoS Data Fields
Unique reference for the CoS
Your sponsor licence reference
The specific role the worker will perform
Standard Occupation Classification code for the role
Annual salary including any allowances
Where the worker will be based
When employment begins
Weekly working hours
CoS Validity and Timing
Validity Period
A CoS is valid for 3 months from the date of assignment. The worker must use it to apply for their visa within this window.
Start Date
The start date on the CoS should reflect when you genuinely expect the worker to begin. It cannot be more than 3 months in the future.
Common CoS Mistakes
- • Incorrect salary (must meet threshold AND going rate)
- • Wrong SOC code for the role
- • Work location not registered on licence
- • Start date too far in future
- • Job title not matching actual duties
Your Obligations After Assigning a CoS
- Ensure the worker starts the job as described on the CoS
- Pay at least the salary specified on the CoS
- Report if the worker does not start within 28 days of the start date
- Report any significant changes to the role, salary, or location
- Keep Appendix D documentation for the worker
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Master Your Sponsor Duties
Understanding CoS is just the start. Our complete guide covers all your obligations as a UK sponsor.
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