A Certificate of Sponsorship (CoS) is an electronic record in the Home Office system that an employer with a valid sponsor licence assigns to an overseas worker. Without a CoS, the worker cannot apply for a Skilled Worker visa or most other UK work visas. This page explains the types of certificate, what they cost, how to request and assign them correctly and which duties apply to the sponsor afterwards.
What a Certificate of Sponsorship is and why it matters
A Certificate of Sponsorship is not a paper document or a letter from the employer. It is a record in the online Sponsorship Management System (SMS), which an employer can access once it holds a sponsor licence. Each certificate has a unique reference number: the worker enters it in the visa application, and the Home Office caseworker uses it to see all the details of the role.
By assigning a CoS, the organisation formally confirms four things: it wishes to sponsor the worker; it is satisfied the worker meets the immigration requirements; it is eligible to sponsor on that route; and it accepts the SMS terms and conditions. This is set out in the Home Office sponsor guidance (part 2). A CoS is therefore not a formality but a legally significant statement by the employer, and the employer’s licence depends on its accuracy.
The reverse is also important: holding a CoS does not guarantee that a visa will be granted. The worker must still score the required points, prove their English, show funds where necessary and pass the remaining checks. The certificate is an essential part of the application, but not the only one.
Key takeaways
- Only an employer with a valid sponsor licence and, with narrow exceptions, an A-rating can assign a CoS
- A Skilled Worker applying from outside the UK needs a defined CoS; applications from inside the UK use an undefined CoS
- The CoS fee on the Worker routes is £525, plus the Immigration Skills Charge for most roles
- The worker must apply for the visa within 3 months of the CoS being assigned
- Assigning the wrong type of CoS or misdescribing the role can cost an organisation its licence
Defined and undefined CoS: what is the difference
The Home Office divides certificates into two types, and they must not be confused: under the Skilled Worker sponsor guidance, assigning the wrong type of CoS is grounds for licence revocation. The choice depends on where the worker is when they apply and which route they are using.
| Feature | Defined CoS | Undefined CoS |
|---|---|---|
| Who it is for | Skilled Workers applying for entry clearance from outside the UK | Skilled Workers applying from inside the UK (extension, change of employer, switching) and workers on all other routes |
| How it is obtained | A separate request through the SMS for each need | From the annual allocation granted to the organisation |
| Who can request it | Level 1 User only | Level 1 User (Level 2 User until 8 March 2027) |
| Decision time | Usually one working day | Extra allocation usually within 12 weeks; a paid 5-working-day service is available |
| Extra fee for the request | None beyond the standard CoS fee | None beyond the standard CoS fee |
| Rating restrictions | Cannot be requested with a B-rating or a suspended licence | A-rating needed; with a B-rating only for extending your own worker’s permission |
| Unused certificates | Requested for a specific need; there is no allocation | Removed at the end of the CoS year; no carry-over |
In practice, confusion is most common among organisations hiring graduates of UK universities or people already on another work visa. Such a candidate applies from inside the country, so they need an undefined CoS from the allocation, not a defined one. Conversely, a candidate who currently lives abroad cannot be assigned an undefined CoS, even if unused certificates remain in the allocation. Before assigning a certificate, it is worth discussing the candidate’s current immigration status with them: it affects the type of CoS, the switching rules and the maximum time they can spend on the route.
The undefined CoS allocation is requested in the licence application and then lasts 12 months. If an organisation on automatic renewal used 10 of its 15 certificates last year, it will receive 10 for the following year. If it needs more, it submits a request to increase the allocation with a justification, and the Home Office may ask for evidence.
Role and employer requirements for assigning a CoS
Before assigning a certificate, the employer must be satisfied that both the role and the candidate meet the rules of the route. For the Skilled Worker visa, the key requirements are set out on the GOV.UK page on job requirements and in Appendix Skilled Worker of the Immigration Rules.
- Skill level. Since 22 July 2025, the job must normally be at RQF level 6 (graduate level). Roles below that level are only eligible if they appear on the Immigration Salary List or the Temporary Shortage List, or if the worker falls under a transitional provision.
- Occupation code. The CoS must state a 4-digit SOC 2020 code, chosen according to the actual duties, not the job title.
- Salary. Usually at least £41,700 a year or the going rate for the occupation code, whichever is higher. A lower threshold applies in some cases — see the guide to Skilled Worker salary thresholds.
- Genuine role. The job must be real rather than created for immigration purposes, and the worker cannot be hired out to a third party as routine labour.
- Employment law. The terms must comply with the National Minimum Wage and the Working Time Regulations.
- Licence rating. Only an A-rated sponsor can assign a CoS. A B-rated sponsor can only assign one to a worker extending their permission from inside the UK whose last grant it sponsored.
What Imperial & Legal checks before a certificate is assigned
- Eligibility of the role at RQF level 6 or under the ISL and TSL
- Selection of the SOC 2020 code based on the worker’s actual duties
- Salary calculation against the £41,700 threshold and going rate
- Identification of the correct certificate type: defined or undefined
- Review of the licence rating and the remaining SMS allocation
- Verification of worker details against passport and UK status
- Assessment of whether the worker can bring family for the role
The requirements for the worker themselves also matter: English at CEFR level B2 for applications under the rules in force from 8 January 2026, proof of funds unless the employer certifies maintenance, and for some occupations a criminal record certificate. More on the language requirement is in the guide to the Skilled Worker English requirement.
How much a CoS costs and what else the employer pays
The cost of hiring an overseas worker is made up of several payments. Some of them the employer is legally required to pay and must not pass on to the worker: the certificate fee and the Immigration Skills Charge (ISC). If an organisation tries to recover these amounts from the worker, directly or through salary deductions, its licence will normally be revoked.
| Payment | Who pays | Amount |
|---|---|---|
| CoS fee (Worker routes) | Employer | £525 per certificate |
| CoS fee (Temporary Worker routes) | Employer | £55 per certificate |
| ISC — small or charitable sponsors | Employer | £480 for the first 12 months and £240 for each further 6 months |
| ISC — medium or large sponsors | Employer | £1,320 for the first 12 months and £660 for each further 6 months |
| Visa fee (applying from outside the UK) | Worker or employer, as agreed | £819 for up to 3 years, £1,618 for more than 3 years |
| Visa fee (applying from inside the UK) | Worker or employer, as agreed | £943 for up to 3 years, £1,865 for more than 3 years |
| Immigration Health Surcharge | Worker or employer, as agreed | Usually £1,035 for each year of the visa |
The ISC is paid in one go for the whole period on the CoS. The maximum sponsorship period on the Skilled Worker route is 5 years, so the maximum charge is £2,400 for a small sponsor and £6,600 for a medium or large one. An organisation is usually a small sponsor if at least two of these apply: annual turnover of £15 million or less, total assets of £7.5 million or less, 50 employees or fewer. The ISC is not payable for certain research and teaching occupation codes, and it is refunded in full if the visa is refused or the worker never starts work. Visa fees and the IHS are taken from GOV.UK guidance on Skilled Worker visa costs; the full picture is in the overview of UK visa fees.
Since 28 October 2026, these two payments have a tax exemption. The CoS fee and the ISC that an employer pays for an employee or prospective employee on the Skilled Worker route are no longer treated as a taxable benefit: no Income Tax arises for the worker and no Class 1A National Insurance contributions for the organisation. The exemption applies whether or not the person has started work and whether or not the visa is granted. The amounts themselves do not change, and sponsor licence fees, visa fees and the IHS are outside the exemption and follow the normal tax rules. The measure was announced at Budget 2026 and will be legislated in Finance Bill 2027 — see the HMRC policy paper.
How to obtain and assign a CoS: step by step
Below is the path from the first consultation to extending the worker’s visa. The timeframes are indicative: a lot depends on whether the organisation already holds a licence, whether a defined CoS is needed and how quickly the Home Office is processing applications at the time.
Consultation and assessment of the role for sponsorship
Defined CoS request or allocation increase
CoS assignment and visa application preparation
Home Office decision and the worker’s start date
Sponsor duties, visa extension and the path to ILR
If the organisation does not yet hold a licence, the process starts earlier with a licence application. According to GOV.UK, the fee is £611 for small businesses and charities and £1,682 for medium and large organisations, and processing usually takes around 8 weeks. An undefined CoS allocation can be requested in the same application.
What information goes on a CoS and what to prepare in advance
The certificate is completed online in the SMS. Most refusals and problems at later compliance checks are caused not by the process itself but by the information entered. It is therefore worth gathering everything before assigning a CoS and checking it against the candidate’s documents and the organisation’s internal records.
- The route on which the worker is being sponsored
- The worker’s personal details: name, nationality, date of birth, passport, address
- The address or addresses where the worker will actually work
- Weekly working hours — an average figure if the pattern varies
- Job title, description of duties and SOC 2020 code
- Start date and end date of employment
- Salary and the elements of pay that count towards the threshold
- Whether a recruitment agency was used and, if so, which one
- Whether the sponsor certifies the worker’s maintenance
- Whether the worker needs an ATAS certificate for certain research roles
On the organisation’s side, it helps to prepare the employment contract or offer letter, the job description, a salary calculation that reflects the hours, and records of how the candidate was recruited. Sponsors must keep recruitment records in line with Appendix D to the sponsor guidance. On the worker’s side, a copy of the passport, details of any current UK visa and proof of English are needed.
CoS validity and visa application deadlines
The most common misunderstanding is confusing the validity of the certificate with the length of the visa. These are different things. The worker must use the CoS in a visa application no more than 3 months after it was assigned. At the same time, they cannot apply more than 3 months before the job start date shown on the certificate. If an organisation assigns a CoS too early while the start date is still far away, the worker may end up unable to make a valid application in time.
The period for which a CoS is assigned is the sponsorship period. On the Skilled Worker route it can be up to 5 years. The visa is usually granted for the sponsorship period plus a short additional period, and after that it must be extended with a new certificate.
Key deadlines to keep in mind when assigning a certificate
- Visa application — no more than 3 months after the CoS is assigned
- Visa application — no earlier than 3 months before the job start date
- Start of work — normally within 28 days of the start date on the CoS
- Reporting a delayed start — within 10 working days after that period
- Undefined CoS allocation — 12 months, with no carry-over of unused CoS
- Change of role or work location — report within 10 working days
- Maximum period of a single Skilled Worker CoS — 5 years
If the start or end date, the salary or the hours change before the application is made, the employer adds a sponsor note to the certificate, which the Home Office caseworker will see. This is possible while the CoS shows the status ‘Assigned’ in the SMS. Once the certificate has been used in an application, changes are reported through the ‘Report migrant activity’ function.
Sponsor duties after a CoS is assigned
Assigning a certificate is not the end of the process but the start of responsibility. From that point, the organisation is accountable to the Home Office for the worker actually doing the stated role on the stated terms. The requirements are set out in detail in part 3 of the sponsor guidance and in practice fall into four areas.
- Right to work checks before employment starts and follow-up checks where permission is time-limited. From 1 October 2026, the scheme also covers other working arrangements — more in the guide to right to work checks.
- SMS reporting: the worker did not start, was absent without permission for more than 10 working days, changed role, location or salary, or left.
- Record keeping for each sponsored worker, including recruitment information.
- Accuracy of the role: the actual duties must match the description on the CoS. If they change so much that the occupation code changes, a new certificate and a new visa application are required.
Breaches are identified during Home Office compliance checks, including unannounced visits. Consequences include a downgrade to a B-rating, suspension or revocation of the licence, and on revocation sponsored workers’ permission is usually curtailed. To reduce the risks, organisations undergo a mock sponsor licence audit or hand routine tasks over to sponsor licence compliance support.
Practical examples: typical CoS situations
CoS situations repeat year after year, even though every organisation feels its case is unique. Here are three scenarios that employers raise most often.
The candidate is abroad, but the organisation only has an undefined allocation
A small IT company found a developer overseas and planned to assign a certificate from its annual allocation. That is not allowed: a candidate applying from abroad needs a defined CoS, requested separately for the specific role. With a well-prepared job description and salary justification, such a request is usually decided within one working day.
A UK university graduate moves onto a work visa
A restaurant group wants to hire a graduate who is currently in the UK on the Graduate visa. This requires an undefined CoS, which means a free place in the allocation. If the allocation has been used up, an increase must be requested first, and the hiring timetable should allow for the time it takes to decide.
Promoting a worker within the organisation
A Skilled Worker was promoted to head of department. If the new role falls under the same occupation code, reporting the change through the SMS is enough. If the code changes, the organisation assigns a new CoS, the worker makes a new application, and additional ISC is paid for any extra period the new certificate adds.
Client stories: CoS and work visas
Obtaining a Certificate of Sponsorship and UK Skilled Worker Visa
Aigul is from Kazakhstan. She is an experienced pharmacist with a medical degree who finds a perfect job in the United Kingdom and wants to relocate...
Obtaining Sponsorship Licence for Pharmaceutical Company To Employ Foreign Specialist
A foreign specialist cannot come to the UK to look for a job; there is no such visa. But they can apply for a work visa after getting employed by a...
Obtaining UK Skilled Worker Visa after Your Employer Changes Their Sponsorship Licence
Li Qian is an experienced chef. He had been working in one of the well-known restaurants in West London for a year. Then the owner decided to set up a...
Reapplying for a UK Skilled Worker Visa after Refusal due to Inaccurate Paperwork
Adel studied at a British university on a UK Student visa. She found a job after graduating. Her future employer was ready to sponsor her so that she...
Accelerated Sponsorship for Food Business in the UK
Andrew Cooper runs a restaurant and a fast-food place in the United Kingdom. He has also acquired a Fish and Chip food store that is quickly developing thanks to the coronavirus pandemic....
Sponsor Licence: How to Hire Foreign Specialists to Work in the UK?
Today’s labour market knows no boundaries. It is common for large, fast growing companies to employ foreign specialists. If your company...
Employers going through this for the first time often say the same thing: the rules can be learned, but the cost of a mistake is too high to learn by trial and error. This is how the head of a pharmaceutical company described her experience.
This was not the first time I came to Imperial & Legal for advice, and they always help me achieve my goal. This time I wanted to employ an Argentinian specialist who looked like the right fit for a vacancy at our London office. However, I had no idea how to prepare the necessary documents, to help the person apply for a UK work visa and relocate to the UK. Imperial & Legal worked their magic again.
Common CoS mistakes and their consequences
Most problems with certificates have nothing to do with dishonesty on the employer’s part. They come from oversight, haste or an attempt to complete the SMS without experience. For the Home Office, however, the reason is secondary: what matters is what the certificate says and what a compliance check reveals.
- Wrong type of CoS. An undefined CoS for a candidate abroad, or a defined CoS used for a role other than the one it was requested for, is direct grounds for licence revocation.
- Inappropriate occupation code. The code is chosen from the job title, while the duties match another code with a different skill level or going rate. This leads to refusal and questions for the sponsor.
- Salary errors. Payments that do not count towards the threshold are included, or the going rate is not adjusted for the working hours.
- Several errors in personal details. One typo can be corrected with a sponsor note, but several errors mean the certificate must be withdrawn and a new one assigned. The fee for a withdrawn CoS is not refunded.
- Poor timing. The CoS is assigned 5–6 months before the start date, and the worker cannot apply within the permitted window.
- Passing on costs. Deducting the CoS fee or the ISC from the worker’s salary normally leads to licence revocation.
- Assigning a CoS to a relative. An SMS user must not assign a certificate to themselves, their partner or a close relative.
If a refusal does happen, it is important to establish the reason quickly: sometimes an administrative review is enough, sometimes a new certificate and a fresh application are needed. More on this in the guide on what to do after a Skilled Worker visa refusal.
CoS support
End-to-end support with your Certificate of Sponsorship
Role assessment
Skill level, SOC 2020 code and salary checked against thresholds
Defined CoS request
Job description and justification for the SMS request
Allocation management
Tracking undefined CoS and requesting an allocation increase
Visa application
Documents, online form and support until the decision
Even when the range of services is clear, the level of support depends on the situation: one organisation only needs a correctly prepared defined CoS request, another needs full support from the licence to the worker’s visa extension.
How CoS rules changed in 2025–2026
Sponsorship rules change several times a year, and many employers only find out after a refusal. Over the last eighteen months, the Home Office has noticeably tightened the requirements for roles that can be sponsored and increased employers’ costs.
- Since 22 July 2025, the baseline skill level for Skilled Worker roles is RQF level 6; roles below it are only eligible through the ISL and TSL or under transitional provisions.
- Workers in roles below graduate level can generally no longer bring a partner and children, unless a transitional provision or another exception applies. Family rules are covered in the guide to the UK dependant visa.
- Since 8 January 2026, new applicants must meet the English requirement at level B2.
- Defined CoS can no longer be requested for codes 6135 and 6136 (care workers and senior care workers): these workers can only be sponsored when applying from inside the UK and meeting additional requirements.
- Since 28 October 2026, the CoS fee and the ISC paid by an employer on the Skilled Worker route are exempt from Income Tax and Class 1A National Insurance contributions; the fees themselves are unchanged.
- The Level 2 User role in the SMS will cease to exist after 8 March 2027, so organisations should review SMS access in advance.
The reform of the route to ILR is also still under discussion. Skilled Workers can currently apply for ILR after 5 years’ continuous lawful residence, but future rules may change this period. The latest status is covered in the guide to earned settlement. This matters for employers because the prospect of ILR often influences a candidate’s decision to relocate.
How to approach assigning a CoS without unnecessary risk
A Certificate of Sponsorship is a short online form with serious consequences. In it, the employer confirms to the Home Office in its own name that the role is genuine, the salary meets the thresholds and the candidate can obtain a visa. The right type of certificate, an accurate occupation code, a careful salary calculation and well-chosen timing determine whether the worker gets a visa and whether the licence attracts questions at the next compliance check.
For the process to run smoothly, it makes sense to start 3–4 months before the worker’s preferred start date: check the licence and the allocation, assess the role, prepare the job description and only then assign the certificate. Answers to the questions employers and candidates ask most often are below.
The information on this page is general, reflects the rules in force in November 2026 and does not replace individual advice: Home Office requirements change regularly, and every application depends on the circumstances of the specific organisation and worker.
