What is a CoS for UK Visa?

A Certificate of Sponsorship (CoS) for UK Visa isn’t a physical document but rather an electronic record. Each CoS has its own number which an applicant needs when applying for a UK visa.

The CoS carries the applicant’s personal details and information about the job they’re offered. But how does one get this CoS? And why is it so important in the UK Visa application process?


The CoS is the backbone of your visa application. Without it, the Home Office cannot evaluate whether your job offer meets the visa requirements. Moreover, your CoS proves that a UK-based employer is willing to vouch for you. It’s an endorsement of your skills and a vote of confidence in your abilities.

Types of CoS

In the complex world of UK immigration, there are two types of Certificates of Sponsorship (CoS): Defined and Undefined. Defined CoS are used to employ Skilled Worker visa applicants based outside the UK. On the other hand, Undefined CoS are used to employ people switching to a visa from within the UK, to employ those on Intra-company visas, and to sponsor others under the points-based system.

Understanding the differences between these two types of CoS can help you determine which type applies to your situation.

Applying for a CoS

You can’t apply for a CoS yourself; your sponsor takes on this responsibility. So, who are these sponsors? What is their role in the CoS application process? 

The CoS isn’t just a number; it’s a snapshot of your life and job offer, from personal details to information about your future role.

How Long Does It Take to Be Approved?

Getting a Certificate of Sponsorship from a UK employer typically takes one working day. However, the processing time could be longer, especially if the Home Office needs to verify specific information.

What Happens if Your CoS is Refused?

A refused CoS can feel like a devastating blow, but it doesn’t mean the end of your UK visa dreams. Understanding why CoS applications are denied and what steps to take next is crucial. 

How Long Is Your CoS Valid?

Each CoS comes with an expiry date. Cos is valid for three months.

What’s the Next Step after Obtaining a CoS? 

After a UK employer has assigned you a Certificate of Sponsorship, a three-month window opens for you to submit your visa application. If this period lapses, the certificate becomes invalid, and there’s a risk that the job offer might slip away.

However, there’s some flexibility as your employer can adjust the certificate’s start and end dates through the sponsor note in the UK Visa Sponsorship Management System.


A Certificate of Sponsorship is crucial for foreign individuals intending to work under a UK employer. Therefore, it’s crucial to ensure that your prospective employer is prepared to assign one to you before you initiate any actions.


I'm Ian, a travel blogger with a background in publishing. My hobby is exploring new places, and here, I share my discoveries from quaint towns and bustling cities. Each trip inspires my next post, inviting you to join me on this exciting journey.