UK Certificate of Sponsorship: What Is CoS and How to Get It in 2025

Skilled Worker Visa

07/03/2025

Once your organisation has successfully obtained a sponsor licence , the next essential step is to assign a Certificate of Sponsorship (CoS) to an individual that you plan to sponsor via the Skilled Worker route. A CoS is an electronic document with a unique reference number that skilled workers have to be assigned by their future UK employer in order to apply for their visa. This article provides a full guide on how to obtain and assign a CoS, the types of CoS available, the associated costs, and expert insights.

What Is a Certificate of Sponsorship?

A Certificate of Sponsorship (CoS) serves as proof that the role being offered to the worker meets the UK government’s visa requirements regarding skills, experience and salary level.

The CoS is assigned and issued through the Sponsorship Management System (SMS) , an online platform provided by the Home Office. It must be assigned by a licensed sponsor to the prospective employee.

The CoS can be assigned to a candidate only 3 months before the expected start date, while the candidate must ensure that their visa application is submitted within the next 3 months after CoS is issued.

Failure to comply with the UK Visas and Immigration (UKVI) regulations regarding the issuance and use of a CoS can result in visa rejections, penalties for the employer, or the revocation of the sponsor licence.

Types of Certificates of Sponsorship

There are two primary types of Certificates of Sponsorship. It’s important to know which one works in your situation: assigning an incorrect type of CoS to your candidates can lead to serious consequences, such as fines, licence revocation, and visa refusals.

1. Defined CoS

This is intended for skilled workers who are applying for entry clearance from outside the UK. Employers must request a defined CoS through the SMS on an ad-hoc basis – e.g., the employer has already identified a candidate to be sponsored, and is requesting allocation of CoS for this particular person.

According to the current processing times, the Home Office decision on a Defined CoS application can take anywhere from 2 days to 6 weeks. There is no option to expedite or escalate this process.

2. Undefined CoS

This type of CoS is for candidates who are already in the UK under a different visa category and wish to switch to the Skilled worker visa. This type of CoS also applies to those who need to extend their current Skilled Worker visa.

The number of undefined CoS must be allocated to the sponsor on the annual basis. The first grant of undefined CoS allocation happens when the Home Office approves the Sponsor Licence application – you need to estimate how many undefined CoS you will require for the year.

If your CoS allocation runs out, additional CoS can be requested via the SMS. However, keep in mind that this type of allocation request takes up to 18 (!) weeks to be approved by using standard processing time. You can always use a priority service by paying £200 to expedite the process, and the allocation will be granted in ~2-3 weeks.

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Understanding the UK Certificate of Sponsorship

Step-by-Step Guide to Requesting and Assigning a Certificate of Sponsorship

Here is a detailed process of how to obtain and assign a CoS through the SMS:

1. Request a Defined or Undefined CoS

A designated Level 1 user in your organisation will request and assign the CoS via the SMS.

For a Defined CoS , make an ad-hoc request through the SMS for each skilled worker you intend to sponsor from abroad. The Home Office will assess the request before approval.
For an Undefined CoS , you are allocated a certain number of certificates annually, depending on the estimate provided during your sponsor licence application.

2. Assign the CoS

Once the CoS is approved or allocated, assign it to the chosen candidate by inputting their details, including job role, salary, and personal information, into the SMS. This will generate a unique reference number (it is advisable to download a PDF copy of CoS from the SMS) that the candidate will use for their visa application.

3. CoS Usage by the candidate

The worker must use the CoS reference number to apply for their Skilled Worker visa within three months of it being issued. They must also ensure that the visa application is submitted no more than three months before their employment start date.

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Costs Associated with CoS

You’ll need to pay a fee when you assign a CoS to your candidate. The cost of a CoS depends on the type of sponsor licence you have.

If you assign a Certificate of Sponsorship to a Skilled Worker or a Senior or Specialist Worker visa holder, you may also be required to pay the Immigration Skills Charge . You must pay the immigration skills charge if they’re applying for a visa from:

outside the UK to work in the UK for 6 months or more
inside the UK for any length of time

There is a list of occupations that don’t require you to pay the Immigration Skills Charge. Additionally, workers assigned certificates before 6 April 2017 or switching from a study visa to a work visa may be exempt. You also don't pay Immigration Skills Charge for dependants of your candidate. More detailed information on those and other exemptions can be found here.

The Immigration Skills Charge must be paid when assigning a CoS. Costs depend on your organisation size and the visa duration.

How Nation.better can help you

If you find yourself in need of assistance with getting a sponsor licence, CoS, Skilled Worker visa for your candidate, or ensuring sponsorship compliance, Nation Better is here to help.

Our team of experts is here to guide you every step of the way, making the whole process a breeze – fill out this form , and our team will contact you with detailed information on how we can support your business in attracting top international talent.

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FAQ Section

1. What is CoS (Certificate of Sponsorship) for a Skilled Worker visa and why is it essential for a Skilled Worker visa application?

A Certificate of Sponsorship for a Skilled Worker visa is an electronic document issued through the Sponsorship Management System (SMS) by a UK employer with a valid sponsor licence. This Certificate of Sponsorship provides a unique reference number that the worker needs for their Skilled Worker visa application. Without a valid Certificate of Sponsorship, an applicant cannot apply for a Skilled Worker visa, making it a crucial step in the hiring process.

2. How do you assign a Certificate of Sponsorship through the Sponsorship Management System (SMS)?

To assign a Certificate of Sponsorship, your organisation’s Level 1 user must submit the required details in the Sponsorship Management System (SMS). To manage CoS processing time efficiently, ensure all details are accurate when submitting the request. For a Defined CoS, apply as soon as possible, considering the Defined CoS processing time. For an Undefined CoS, monitor your annual allocation and submit early to account for the Undefined CoS processing time and avoid delays with your Skilled Worker visa applications.

3. What is the typical UK CoS processing time for a Defined CoS and an Undefined CoS when applying for a Skilled Worker visa?

The UK CoS processing time for a Defined CoS is 2 days to 6 weeks. For an Undefined CoS, it can take up to 18 weeks unless you pay for priority processing, which reduces the Undefined CoS processing time to 2-3 weeks. Always check your Certificate of Sponsorship status in the Sponsorship Management System (SMS) to avoid delays in your Skilled Worker visa application.

4. When should a Certificate of Sponsorship be assigned to support a Skilled Worker visa application, considering the CoS processing time?

A Certificate of Sponsorship must be assigned no more than three months before the job's start date. Given the Certificate of Sponsorship processing time, employers should factor in the Defined CoS processing time of up to 6 weeks or the Undefined CoS processing time of up to 18 weeks to avoid missing critical deadlines. Delays in CoS processing time can cause serious issues, including invalid Skilled Worker visa applications and potential non-compliance with your sponsor licence duties.