A Certificate of Sponsorship isn't a certificate, and you don't receive one, you issue it. If you hold a sponsor licence, a CoS is the electronic record you create to sponsor a specific worker for a specific job. It's the thing that lets them apply for their visa, and it's entirely your responsibility to get right.
This guide is written for the employer doing the issuing, not the worker waiting on one. It covers what a CoS actually is, the two types and which you need, how to assign one, and what it costs you in 2026. If you don't have a licence yet, that comes first: start with our sponsor licence application guide.
What is a Certificate of Sponsorship?
A CoS is a digital record, not a paper document. You create it through the Sponsorship Management System (SMS), the Home Office portal that comes with your licence. Each CoS carries a unique reference number and sets out the job: the role, the salary, the hours, the start date, and the worker it's assigned to. The worker then enters that reference number on their visa application.
Think of it as your formal declaration to the Home Office that this is a genuine job, at a genuine rate, that genuinely needs sponsoring. When the caseworker assesses the worker's visa, they're checking the visa against what you declared on the CoS. If the two don't match, or if the role doesn't stand up, the problem lands on you as much as the worker.
Most Certificates of Sponsorship are issued for the Skilled Worker visa. You'll also see the term attached to other routes, but for the majority of UK employers, "CoS" means a Skilled Worker sponsorship.
Defined vs undefined: which CoS do you need?
This is the distinction that trips up first-time sponsors, and it comes down to where your worker is applying from.
A defined CoS is for a worker applying for a Skilled Worker visa from outside the UK. You request each one individually through the SMS, and the Home Office approves it (usually within a day or two) before you can assign it. You don't hold a stockpile of defined certificates; you request them as you need them.
An undefined CoS is for a worker already in the UK who's switching into the Skilled Worker route or extending their stay. These come from your annual allocation: a pool of certificates you apply for and hold, ready to assign without individual approval each time.
The practical version: hiring someone from abroad means requesting a defined CoS for that hire. Sponsoring someone already here means drawing from your undefined allocation. Get the type wrong and the worker can't apply, so it's worth confirming before you start.
How to assign a Certificate of Sponsorship
Once you're licensed and you have the right type of certificate available, assigning a CoS runs like this. You log into the SMS, select the worker and the job, and enter the details: the occupation code, the salary, the hours, the start and end dates, and the worker's personal information. You confirm the role meets the skill level and pays at least the going rate or the £41,700 general salary threshold, whichever is higher. You pay the CoS fee. The system generates the reference number, and you pass it to the worker so they can apply.
Accuracy is everything here. The salary you enter has to match what you'll actually pay. The occupation code has to be the right one for the role. Mistakes on a CoS don't just risk the worker's application, they're the kind of thing a Home Office audit flags later. Our key personnel guide covers who in your organisation is allowed to assign certificates, because not every user can.
What does a Certificate of Sponsorship cost?
The CoS assignment fee for a Skilled Worker is £525 in 2026, and it's flat: it doesn't rise with the length of the visa. You pay it each time you assign a certificate, and it's legally your cost as the employer. You cannot pass it to the worker, deduct it from their pay, or make it a condition of the offer. Doing so can cost you your licence.
The £525 is rarely the number that matters most, though. The bigger cost attached to sponsoring a worker is the Immigration Skills Charge (ISC), paid at the same time you assign the CoS:
- Certificate of Sponsorship fee: £525 (small and large sponsor).
- Immigration Skills Charge, first 12 months: £480 for a small sponsor, £1,320 for a large sponsor.
- Immigration Skills Charge, each further six months: £240 for a small sponsor, £660 for a large sponsor.
So a small sponsor issuing a CoS for a three-year hire pays £525 plus £1,440 in ISC. A large sponsor pays £525 plus £3,960. That's before the worker has paid a penny towards their own visa.
For temporary routes and the Scale-up route, the CoS fee is lower, at £55, and the Immigration Skills Charge doesn't apply. Most employers, though, are issuing the £525 Skilled Worker certificate.
To see the full cost of sponsoring a worker, licence and CoS and ISC together, run your own numbers:
Try the Sponsor Licence Calculator
For a deeper breakdown of the CoS fee on its own, including the temporary-route rates, see our Certificate of Sponsorship cost guide.
Managing your CoS allocation
Your licence comes with an allocation: the number of undefined certificates you can hold in a given year. When you first apply, you estimate how many you'll need, and the Home Office grants a figure. Run low and you request an increase through the SMS, with a justification for why you need more.
The thing to plan for is timing. A defined CoS for an overseas hire takes a day or two to approve, which is fine if you've built it into your recruitment timeline and a problem if you're issuing an offer for a Monday start. Employers who sponsor at any volume treat their allocation as a live number to watch, not a form they filled in once.
Where employers go wrong with CoS
A few mistakes come up again and again. Assigning a CoS with a salary that doesn't match the contract. Choosing the wrong occupation code, so the going rate the Home Office expects doesn't line up. Issuing a defined CoS when the worker needed an undefined one, or the reverse. Leaving the start date so tight that a visa delay derails the hire. And treating the CoS as the end of the process, when in fact it starts a set of ongoing reporting duties that run for as long as you sponsor the worker.
None of these are exotic. They're the everyday slips of managing sponsorship on a spreadsheet, and they're exactly what a compliance visit is designed to catch.
Before you issue your first CoS
If you're still setting up, the certificate is one of the last steps, not the first. Get the licence, name your key personnel, understand your duties, then issue. Our free checklist covers the documents and decisions that come before you're ready to sponsor anyone:
Download the Sponsor Licence Application Guide
Certificate of Sponsorship FAQs
What is a Certificate of Sponsorship?
It's a digital record a licensed UK employer creates to sponsor a specific worker for a specific job. It carries a unique reference number the worker uses to apply for their visa. It confirms the role, salary, hours, and dates to the Home Office.
How much does a Certificate of Sponsorship cost in 2026?
The CoS fee for a Skilled Worker is £525, paid by the employer each time you assign one. Temporary Worker and Scale-up certificates cost £55. On top of the CoS fee, most Skilled Worker sponsors also pay the Immigration Skills Charge when they assign the certificate.
What's the difference between a defined and undefined CoS?
A defined CoS is for a worker applying from outside the UK, requested individually and approved by the Home Office before you assign it. An undefined CoS is for a worker already in the UK, drawn from your annual allocation without individual approval.
Who pays for the Certificate of Sponsorship?
The employer. You cannot legally recoup the CoS fee, the sponsor licence fee, or the Immigration Skills Charge from the worker. The worker pays their own visa application fee and health surcharge.
How long does a CoS take to issue?
An undefined CoS can be assigned immediately from your allocation. A defined CoS for an overseas worker usually takes one to two working days for the Home Office to approve before you can assign it.
Does a CoS guarantee the worker gets a visa?
No. The CoS lets the worker apply, but the Home Office still assesses their visa on its own merits, including their identity, finances, and English where required. A CoS that doesn't match the actual job can cause the visa to be refused.
One allocation, every certificate, in one place
A Certificate of Sponsorship looks like a form. It behaves like a legal commitment: the moment you assign one, you've told the Home Office something it can hold you to for years. Get the salary, the code, or the type wrong and you find out at the worst possible moment.
Nationally, only around 35% of CoS requests succeed first time. For Borderless customers, it's 96%. Borderless Immigration gives sponsors one system for every certificate: your allocation, each CoS you've issued, the details behind it, and the reporting deadlines that follow. Book a demo to see how it handles your next hire.
Automate Home Office Audits with Borderless
The Borderless platform provides a centralized system for all sponsorships, automating reminders for key tasks and ensuring best practices across your organization, simplifying audit preparation and ongoing compliance.
