What is the Difference Between A Defined CoS and An Undefined CoS?

Disclaimer: The information in this blog is accurate as of its publication date. Any updates after that date are not reflected here.

Certificates of Sponsorship (CoS) are virtual documents generated in the sponsor’s Sponsor Management System (SMS) portal.

Sponsored workers who are making a visa application to change sponsor or who are switching into the Skilled Worker route from another type of UK visa, from inside the UK, will require an undefined Certificate of Sponsorship to make a valid Skilled Worker visa application.

Sponsors can apply for a “quota” or number of undefined Certificate when applying for a sponsor licence. They are at liberty to increase the number of undefined Certificates throughout the year

Defined CoS, on the other hand, are assigned to sponsored workers applying outside the UK for a Skilled Worker visa only. As explained below, you will need to apply for each defined CoS (on a case-by-case basis) before it can be created and assigned.

The term “Defined” and “undefined” CoS replaced the older terminology which existed prior to December 2020 when the CoS were known as “restricted” and “unrestricted” CoS.

As with many aspects of the immigration and sponsorship system, there are many subtle rules that must be understood in order to remain compliant. In this article, we will explain the key differences between a defined CoS and an undefined CoS.

What is a defined Certificate of Sponsorship?

As a sponsoring employer, you will need to create and assign a defined Certificate of Sponsorship (CoS) if you are hiring a foreign national who is applying for a Skilled Worker visa from outside the UK. As the UKVI guidance states, “You must apply for a defined CoS if you want to recruit a migrant under Skilled Worker who will be applying for leave to enter the UK from overseas”. To assign a Defined CoS, you will need to apply for a defined CoS through the SMS portal, and this must be reviewed (by the UKVI) approved before it can be created and assigned to the sponsored worker.

What is an undefined Certificate of Sponsorship?

As a sponsoring employer, you will need to create and assign an undefined Certificate of Sponsorship (CoS) if you are hiring a foreign national who is applying for a Skilled Worker visa from inside the UK.

When you applied for your sponsor licence, you would have been asked to provide an estimate of the number of undefined CoS you require in your first year. You would also have been asked to provide evidence to justify the number of CoS you have requested. If you already have a “quota” of certificates you do not need to apply for an undefined CoS; you can proceed to create and assign the previously approved CoS.

There is no limit (cap) on how many undefined CoS you can assign; what matters is that each sponsored worker must be eligible for the type of work visa they are applying for. In addition, you pay £199 for each Skilled Worker CoS you assign.

How to apply for a defined Certificate of Sponsorship

You will need to apply for a defined CoS through the UKVI sponsorship management system (SMS) before it can be created and assigned. UKVI provides a detailed manual (‘SMS guide 12: restricted certificates of sponsorship) which details how to apply for a defined CoS.

To apply for a defined CoS, you will need to complete the following steps on the SMS portal:

1. Access your SMS system
2. Go to the ‘Workers’ page
3. Select ‘Defined CoS’
4. On the ‘Apply for defined CoS’ page, click ‘Apply for defined CoS’
5. Enter the number of CoS you need – then click ‘Next’ (if necessary, you can apply for more than one defined CoS at once as long as the employment details are the same on each).
6. Enter the details of the employment and then click ‘Next.’
7. Check the CoS application details are correct
8. Review the declaration and click to agree to the terms of the CoS, and
9. Select Submit – you will now see a request number for the defined CoS.

Once you have submitted the defined CoS application, it will be reviewed by UKVI. In most cases, defined CoS applications are processed within one working day. In some cases, UKVI may request more details regarding the role and/or candidate before approving your application.

When applying for a defined CoS, there are some important points to bear in mind:

• You must hold an A-rated sponsor licence in the Skilled Worker category in order to apply for defined CoS. If your sponsor licence has been downgraded, you will not be able to apply for a defined CoS.
• You may be asked to confirm if the candidate has a role in a shortage occupation or if they have a PhD in a relevant subject if they do not meet the minimum salary requirements and hence need to trade points.

How to create and assign a defined Certificate of Sponsorship

Once your defined CoS has been approved by UKVI, it can be created and assigned to your sponsored worker. To create and assign an approved defined CoS, you will need to complete the following steps on your UKVI SMS portal:

1. Access your SMS system
2. Go to the ‘Apply for defined CoS’ page
3. Click ‘Granted applications – create and assign defined CoS’
4. Select the relevant approved CoS application, then click ‘Next.’
5. On the ‘Granted applications – create and assign defined CoS’ page, click ‘Create’ (you will need to repeat this step if you applied for more than one defined CoS)
6. On the ‘Create a CoS’ page, enter the details of your sponsored worker and then click ‘Save.’
7. Click ‘Assign’
8. Review the declaration and tick the box to agree to the terms
9. Pay the CoS fee, and
10. Once the payment has been completed, you will be provided with the CoS reference number.

How to apply for an undefined CoS

You can use the UKVI SMS portal to increase your Certificate of Sponsorship (CoS) allocation or request an annual Certificate of Sponsorship (CoS) allocation. The steps you will need to complete are as follows:

Renewal of annual allocation

Please note, on 23^rd March 2023, UKVI wrote to sponsors confirming that Skilled Worker sponsor annual allocations will be automatically renewed each year (rather than having to make a manual request at the start of each CoS year). The number you will receive will be equal to the number of CoS you assigned in the 12-month period prior to your new allocation being automatically created. To check your automatic renewal allocation, please complete the following steps.

1. Access your SMS system
2. Go to the ‘Licence summary, applications and services’ page
3. Click ‘Request renewal of annual CoS/CAS allocations’
4. On the Request renewal of annual allocation, you can see if your CoS allocations are due to be renewed automatically. If UKVI has sent you an email reminding you to apply, you will need to submit a manual application. To do this, click ‘Add a request’ next to the relevant sponsorship route.
5. Enter the increased number of CoS that you require and provide a reason
6. Click ‘Save’ and
7. Click ‘Submit’

Request CoS allocation Increase

1. Access your SMS system
2. Go to the ‘Licence summary, applications and services’ page
3. Click ‘Request CoS/CAS allocation increase’
4. Click ‘Add a request’ next to the relevant sponsorship route
5. Enter the increased number of CoS that you require and provide a reason
6. Click ‘Save
7. Click ‘Submit’

The service standard for undefined CoS requests is officially 18 weeks, but it normally takes UKVI 4-12 weeks to consider and decide requests. If necessary, you can use the priority change of circumstances service to request changes to your undefined CoS allocation. This can be used both to request an additional CoS allocation and to renew your annual allocation. 

To use this service, you must be A-rated and have submitted the request via your SMS. You will then need to email postlicencepriorityservice@homeoffice.gov.uk and attach a completed Worker and Temporary Worker priority request form. If you are selected, you will be emailed a link to pay a fee of £200. The fee payable is per quota requested (overall number of CoS requested in the application), not per CoS, indivudally. Your priority CoS request will normally be handled within 5 working days.

Frequently Asked Questions

What is the difference between defined CoS and undefined CoS?

First, defined CoS serves workers applying for a Skilled Worker visa from outside the UK. Next, you must request each defined CoS via the SMS portal and await UKVI’s one-day approval before creating and assigning it. In contrast, undefined CoS uses your annual allocation for workers switching visa or changing sponsor inside the UK—no UKVI pre-approval is required for each assignment.

What are the two types of CoS?

First, you have defined CoS, which you apply for one-by-one when hiring migrants based overseas. Then, you have undefined CoS, which draws on your annual quota for internal applications—such as visa switches or changes of employer inside the UK. These two replace the old “restricted” and “unrestricted” certificates.

What is a defined sponsorship certificate?

First, a defined sponsorship certificate (defined CoS) is a virtual document you request via your SMS portal for each overseas hire. Next, UKVI reviews your defined CoS application—usually within one working day—and only then can you create and assign the certificate to your sponsored worker. Finally, you pay the CoS fee upon assignment.

How long does it take for an undefined CoS to be approved?

First, you don’t need UKVI approval to assign undefined CoS from your existing annual allocation. However, if you request an increase in your undefined CoS quota, UKVI’s official service standard is 18 weeks. In practice, sponsors typically receive a decision within 4–12 weeks, and you can use a priority service to expedite requests to about five working days for an extra fee.

At A Y & J Solicitors, we have handled over 100s of Sponsor Licence Application and Skilled Worker Applications. With a 95% success rate, we have achieved an overall track record of 5,000+ successful immigration and visa cases through our result-driven approach to every application. We take on each client with the genuine intention to provide our undivided care and attention to their case. We guide you through every step of your Sponsor Licence process, so you can trust the experts to manage your application and work toward your success.

Why A Y & J Solicitors?

With over thousands of successful immigration cases to our name, A Y & J Solicitors has built its reputation on trust, care, and real results. Over the 15+ years of working in UK immigration law, we’ve helped individuals and businesses confidently navigate sponsor licences, visas, and ILR applications. We’re proud to be recognised by The Legal 500, but it’s our clients’ peace of mind that matters most. When you work with us, you get clear advice, honest support, and a team that’s truly on your side.