If you are an employer trying to bring skilled talent to the UK, or a foreign worker hoping to secure a sponsored role, understanding the certificate of sponsorship is essential. This electronic record lies at the heart of the UK’s work visa system, serving as an electronic document rather than a paper certificate, and without one, most sponsored visa applications simply cannot proceed.
A certificate of sponsorship is the formal confirmation that a licensed UK employer has offered a genuine role to a specific migrant worker. It contains all the key details that UK Visas and Immigration need to assess the visa application, from job title and salary to start date and occupation code. For routes like the skilled worker visa, the certificate of sponsorship is not optional—it is mandatory.
Many employers find themselves confused about the difference between defined and undefined certificates of sponsorship. In the context of UK immigration and visa sponsorship, defined certificates are specifically required for skilled workers applying from outside the UK. Workers often struggle to find a sponsoring employer willing to navigate the system. Tight start dates add pressure, and any errors on the certificate of sponsorship can lead to visa refusals or compliance problems down the line.
In this blog, we’ll explore what certificate of sponsorship UK is and why it matters for both employers and workers. You’ll get a clear take on the types of CoS, how to assign one correctly, avoid common pitfalls, and navigate costs and compliance with confidence. Plus, we’ll point you to official UK guidance so you know you’re following the rules.
What is Certificate of Sponsorship?
A certificate of sponsorship is an electronic record that a licensed UK employer creates when they want to sponsor a foreign worker for a visa. Despite the name, it is not a physical document or paper certificate; instead, it is an electronic document. It exists as a digital entry within the Home Office’s sponsorship management system.
Each certificate of sponsorship carries a unique reference number. The sponsored worker uses this cos number when submitting their visa application to UK Visas and Immigration. Without this reference number, the applicant cannot complete the online application form for most sponsored work routes.
The certificate of sponsorship confirms several critical details about the job offer and the worker:
- The sponsoring organisation’s sponsor licence number
- The job title and a summary of duties
- The relevant SOC code (Standard Occupational Classification)
- The salary being offered, including any allowances
- The work location
- The proposed start date and, where applicable, end date
- Whether the immigration skills charge applies to the role
The visa application must normally be submitted within three months of the certificate of sponsorship being assigned. The CoS must be used by the worker to apply for their visa within three months of being assigned. It should also be lodged no more than three months before the job start date shown on the CoS. If the worker applies too early or too late, the application can be refused.
The certificate of sponsorship is required for the Skilled Worker route, Senior or Specialist Worker (Global Business Mobility), Scale-up Worker (during the sponsorship phase), and most Temporary Worker categories. Without a valid CoS, visa applicants on these routes cannot proceed.
Responsibility for assigning a correct certificate of sponsorship lies with the licensed sponsor. Only licensed sponsors can issue certificates through the sponsorship management system. However, any errors—whether in salary, SOC code or personal details—will directly affect the worker’s visa outcome. Getting the CoS right is essential for both parties.
Types of Certificate of Sponsorship
In December 2020, the Home Office replaced the old “restricted” and “unrestricted” categories with a new system: defined and undefined certificates of sponsorship. This change aligned with the introduction of the new points-based immigration system.
The key difference between defined and undefined CoS depends mainly on two factors: where the worker is applying from and which visa route they are using.
For the skilled worker visa, sponsors may need to use either defined or undefined certificates of sponsorship depending on the circumstances. Most other worker categories—such as Global Business Mobility routes and Temporary Worker visas—use only undefined CoS.
Sponsors holding a provisional licence can only issue one certificate of sponsorship until they achieve an A-rating. An A-rating is required to issue additional certificates beyond the initial one.
| Type | When used | Who it applies to |
| Defined CoS | Worker applying from outside the UK | Skilled Workers abroad |
| Undefined CoS | Worker applying from inside the UK | In-country Skilled Workers, GBM, Temporary Workers |
Understanding which type your situation requires is the first step to getting the certificate of sponsorship process right.
Defined certificate of sponsorship (for Skilled Workers outside the UK)
A defined certificate of sponsorship is required when the individual is applying for a skilled worker visa from outside the UK. Defined certificates are specifically for Skilled Worker applicants applying from outside the UK, while undefined certificates are for applicants already in the UK. This applies to foreign nationals who have not yet entered the country and need entry clearance to take up their role.
Before an employer can request a defined CoS, they must already hold an A-rated skilled worker sponsor licence. Sponsors with a provisional rating or B rating cannot assign new certificates of sponsorship.
To request a defined certificate of sponsorship, an authorising officer or Level 1 user logs into the sponsorship management system (SMS) account and navigates to the defined CoS section. They enter full details of the role, including job title, duties, SOC code, salary, weekly hours, and start date. The sponsor must also confirm genuineness statements about the role and the worker’s suitability.
UKVI usually processes defined CoS requests within one working day. However, further checks may be needed if the role description is unclear, the salary is close to the minimum threshold, or there are questions about whether the position is genuine.
Once approved, the defined certificate of sponsorship appears in the SMS system. The sponsor must then formally assign it to the named worker. At this point, the cos fee is payable.
Undefined certificate of sponsorship (for in-country and other workers)
Undefined certificates of sponsorship cover a wider range of situations. They are used for skilled workers applying from inside the UK—for example, those switching from a Student visa or Graduate route. They also apply to practically all other sponsored worker categories, including GBM Senior or Specialist Worker, UK expansion worker, intra company transfer (legacy cases), Creative Worker, and Charity Worker routes.
When applying for a sponsor licence, employers must estimate how many undefined CoS they will need for the first 12 months. This process involves determining how many undefined certificates will be required in the first year, as part of the sponsor licence application. Employers must provide justification for each category, explaining their recruitment plans and business needs. Once the sponsor licence is approved, UKVI issues an annual allocation of undefined certificates of sponsorship. This allocation is visible in the sponsor’s sms account.
Unlike defined CoS, sponsors assign undefined CoS directly from their allocation without needing to seek individual approval from UKVI beforehand. This makes the process faster for in-country applications.
There is an important compliance point here: sponsors should not inflate CoS allocation requests without genuine evidence. Doing so can trigger compliance visits from the Home Office or lead to allocation reductions. UKVI expects sponsors to justify their numbers with business plans, contracts or clear recruitment projections.
Documents Required for Certificate of Sponsorship UK
When applying for a Certificate of Sponsorship (CoS) for a skilled worker visa or other sponsored worker routes, employers must ensure they have a valid sponsor licence and access to the Sponsorship Management System (SMS). The process of assigning a CoS is managed entirely through the SMS account, and the certificate itself is an electronic record rather than a physical document.
To complete a CoS application, the sponsoring organisation must enter detailed information about the job offer and the foreign worker. This includes the job title, salary, SOC code, start date, end date (if applicable), and work location. These details are essential for UK Visas and Immigration (UKVI) to assess the visa application and ensure compliance with current immigration rules.
While the SMS does not require employers to upload supporting documents at the point of assigning a CoS, it is crucial to have all relevant documentation on file. For certain visa types or in specific circumstances, UKVI may request further information or evidence to justify the sponsorship. For example, if a Resident Labour Market Test is required under previous or transitional rules, a report demonstrating genuine recruitment efforts may need to be provided. Employers should also be prepared to supply business plans, contracts, or other evidence if requesting an increase in their allocation of undefined certificates.
The authorising officer is responsible for ensuring that all information entered in the SMS is accurate and that the organisation meets all sponsorship licence conditions. Employers should keep thorough records in their HR systems, including scanned copies of employment contracts, job descriptions, and any correspondence with visa applicants. This is vital for demonstrating compliance during Home Office audits or if further checks are triggered.
It is important to note that the number of undefined certificates available to a sponsor is set annually, and employers should only request as many as they can justify with genuine business needs. The CoS fee and, where applicable, the immigration skills charge must be paid when assigning a new CoS.
For the most up-to-date sponsorship guidance and to ensure you meet all eligibility requirements, always consult the UKVI website or seek professional immigration advice. Staying compliant with UK immigration law and Home Office requirements will help avoid delays or refusals in the visa application process for your skilled workers and foreign nationals.
How to Get a Certificate of Sponsorship UK
For HR managers and business owners, understanding the application process for obtaining and assigning a certificate of sponsorship is essential. The steps below provide a clear overview aimed at SMEs and larger organisations alike.
Only employers with a valid sponsor licence can assign a certificate of sponsorship. The sponsor management system (SMS) is the platform used to manage sponsor licences and process CoS requests. Within the sponsorship management system, only Level 1 users and authorised Level 2 users can perform this task. The authorising officer is ultimately responsible for ensuring compliance.
The process differs slightly for defined and undefined CoS, but the core principles are the same:
Step 1 – Hold an appropriate sponsor licence
Different licence types exist for Skilled Worker, Global Business Mobility, Creative Worker, and other routes. Key requirements for a sponsor licence include:
- The organisation must be genuine, based and trading lawfully in the UK
- Appropriate hr systems must be in place for tracking and reporting on sponsored workers
- The employer must be capable of meeting ongoing sponsor duties
An A-rating is required for sponsors to issue multiple certificates of sponsorship; new sponsors are usually given a provisional rating and must upgrade to an A-rating to access additional certificates.
The sponsorship licence application fee depends on the size and type of organisation. As of the most recent Home Office fee schedule, smaller sponsors pay around £536 while medium and large sponsors pay £1,476. Certain public sector and charitable bodies may qualify for reduced fees. Always confirm the current status of fees on GOV.UK before applying.
Step 2 – Request a defined certificate of sponsorship (if required)
This step applies only when sponsoring a skilled worker who is outside the UK at the time of application, as defined certificates are specifically used for this purpose. To request a defined CoS:
- Log in to the sms account as a Level 1 user
- Navigate to “Create and assign – defined CoS”
- Input full job details: title, duties, SOC code, salary, weekly hours, start date
- Confirm the genuineness statements
- Submit the request to UKVI
Typical processing time is one working day. However, complex roles, borderline salaries, or concerns about genuineness can attract further scrutiny and delay approval. A poorly drafted role description or incorrect SOC code can lead to refusal of the defined certificate of sponsorship. Even if the CoS is approved, errors may cause the worker’s visa application to be refused later.
Step 3 – Create and assign the certificate of sponsorship
Once a defined CoS is approved, or where undefined CoS allocation already exists, the sponsor must create and assign the certificate of sponsorship in the SMS to a specific individual.
Key details that must be entered accurately include:
- Worker’s full name (matching passport exactly)
- Date of birth
- Nationality
- Passport number
- SOC code
- Job title and duties summary
- Salary (including any allowances)
- Work address
- Weekly working hours
- Start date and, where relevant, end date
By assigning the certificate of sponsorship, the sponsor confirms that the role meets the Skilled Worker skill level, the salary threshold (including going rate and any tradeable points), and that the job offer is genuine. The sms system generates the CoS reference number once assignment is completed and fees are paid.
Sponsors should download or save the CoS summary for their records and send the reference number and key job details securely to the worker.
Step 4 – Worker uses the certificate of sponsorship for their visa
The sponsored worker must include the certificate of sponsorship reference number in their online visa application form. For the skilled worker visa, this is completed on GOV.UK.
The visa application should be lodged within three months of the certificate of sponsorship being assigned, and before the expiry date shown on the CoS.
Visa processing times vary. As of 2025, standard processing for most overseas Skilled Worker applications is around three weeks, with priority options available for faster decisions. The CoS must still be valid on the date UKVI makes their decision.
Sponsors and workers can instruct Axis Solicitors to handle both the CoS and visa application together. This ensures consistency in job details, salary information and maintenance evidence across both stages.
Certificate of Sponsorship Allocation and Increases
Allocation refers to the maximum number of undefined certificates of sponsorship a sponsor can assign in a given allocation year. Understanding how this works is important for recruitment planning.
During the sponsor licence application, employers must forecast how many undefined CoS they will need for skilled workers and Temporary Workers, specifically determining how many undefined certificates will be required. They must provide supporting explanations for these numbers, based on genuine business needs.
UKVI can grant the requested allocation in full, reduce it, or request further information before making a decision. Unused certificates of sponsorship are usually removed at the end of the allocation period.
If recruitment needs rise unexpectedly, sponsors can request a follow-on allocation or an in-year increase through the sms system. UKVI may ask for evidence such as:
- Business plans showing growth projections
- Contracts requiring additional staff
- Recruitment data demonstrating unmet labour needs
Failure to manage allocation correctly can delay recruitment when no CoS are left to assign. It may also cause UKVI to question the genuineness of roles if allocation requests seem inflated.
Costs and Charges Linked to a Certificate of Sponsorship
There are two main categories of costs associated with a certificate of sponsorship: the CoS assignment fee and, in many cases, the immigration skills charge.
Certificate of sponsorship fee
The cos fee is paid each time a new certificate of sponsorship is assigned. The amount depends on the visa route and whether the sponsor is classed as a small or charitable sponsor or a medium/large sponsor.
For Skilled Worker CoS, smaller sponsors typically pay a lower fee per certificate, while larger sponsors pay more. Always verify the current fee levels on GOV.UK before budgeting, as these figures are updated periodically.
Immigration Skills Charge
The immigration skills charge (ISC) generally applies to Skilled Worker and GBM Senior or Specialist Worker routes. It is an additional charge designed to encourage investment in training the domestic workforce.
The ISC does not apply to most Temporary Worker categories. Certain exemptions exist, including some health and care roles and PhD-level occupations. Check the current list of exemptions when planning your sponsorship.
Other costs to budget for
Beyond the CoS-related charges, the worker or employer should budget for:
- Visa application fee
- Immigration Health Surcharge (where applicable)
- Biometric enrolment fees
- Priority processing charges (optional)
Common Mistakes with Certificates of Sponsorship
UKVI regularly refuses visa applications or takes compliance action where certificate of sponsorship details are inaccurate or misleading. Avoiding these errors is essential for both sponsors and sponsored workers.
Common mistakes include:
- Using the wrong SOC code for the role
- Under-declaring salary or weekly hours
- Setting unrealistic start dates
- Assigning a certificate of sponsorship to someone who does not actually meet the skills or English language requirements
- Spelling errors in names or passport numbers
- Using an expired passport number
- Mismatched work locations compared with the employment contract
Home Office statistics indicate a 12% rejection rate for CoS-linked visa applications, often due to skill mismatches or invalid allocations. One 2025 case saw a hospitality chain fined £20,000 for issuing certificates of sponsorship with understated salaries, resulting in licence downgrade and recruitment halts.
Correcting errors
Minor errors can sometimes be corrected using a sponsor note on the certificate of sponsorship within the sms system. More serious errors may require cancelling the CoS and assigning a fresh one, with new fees payable. If an employee’s circumstances change, the original certificate must be cancelled before a new one is issued.
How Axis Solicitors Can Help with Your Certificate of Sponsorship
Axis Solicitors are experienced UK immigration solicitors with strong expertise in sponsor licensing and certificate of sponsorship work. We understand the pressures employers face when recruiting foreign nationals, and the anxieties workers feel when their visa depends on their sponsor getting the CoS right.
Our core services include:
- Applying for new sponsor licences (Skilled Worker, GBM, Temporary Worker routes)
- Advising on defined vs undefined certificates of sponsorship
- Drafting and checking CoS entries before submission
- Managing allocation increases and justification statements
- Preparing responses to UKVI compliance enquiries
- Representing sponsors at compliance visits and audits
- Handling visa applications for sponsored workers
We support employers of all sizes, from small businesses to national organisations with multiple sites across England and Wales. For individual workers, we can help find a sponsoring employer or challenge refusals linked to CoS problems.
Request a free initial consultation about your certificate of sponsorship and Skilled Worker visa plans.
