The Certificate of Sponsorship (CoS) is one of the core components of the UK’s sponsored work visa system. It serves as the official confirmation from a licensed sponsor that a migrant has a genuine job offer in the UK which meets the requirements under the Immigration Rules. Without a valid CoS, an individual cannot apply for most sponsored work visas, including the Skilled Worker route, Health and Care Worker route, Global Business Mobility visas, and various Temporary Worker categories.
This guide provides a detailed overview of the Certificate of Sponsorship. It explains what a CoS is, why it is required, and how it functions within the UK immigration system. It examines the different types of CoS, how employers apply for and assign them, and the compliance responsibilities attached. It also highlights common risks and mistakes that can jeopardise a sponsor licence, giving clarity to employers, HR teams, and visa applicants alike.
A CoS is not a paper document but an electronic record created via the Home Office’s Sponsor Management System (SMS). Each certificate carries a unique reference number which must be included in the worker’s visa application. This reference links the application to the sponsoring employer’s confirmation that the role is genuine, meets the required skill and salary thresholds, and complies with immigration law.
For employers, understanding how the CoS system works is critical to navigating the sponsorship process effectively. Errors in assigning a CoS or breaches of related duties can result in visa refusals, civil penalties, or even loss of the sponsor licence. For workers, the CoS provides the key link between a confirmed job offer and the ability to obtain permission to live and work in the UK.
Section A: What is a Certificate of Sponsorship?
The Certificate of Sponsorship is the formal mechanism that underpins the UK’s sponsorship regime. Despite its name, it is not a certificate in paper form, but an electronic record confirming a licensed sponsor’s offer of employment or engagement to a migrant worker. Each CoS is issued with a unique reference number that the worker must use when submitting their visa application.
The CoS acts as proof that the sponsoring employer has carried out the necessary checks, confirmed the role meets Immigration Rules, and accepted responsibility for the worker’s compliance. Without this digital confirmation, the Home Office will not consider a sponsorship-based visa application.
1. Definition and purpose
A Certificate of Sponsorship is created through the Sponsor Management System, the Home Office’s online platform for licensed sponsors. It confirms that a UK-based organisation with a valid sponsor licence is offering a role that meets the requirements of the relevant visa category.
Its purpose is twofold: first, to ensure that only licensed sponsors can offer employment to non-UK nationals; and second, to provide the Home Office with a clear mechanism to track and verify that sponsored employment is genuine, necessary, and compliant with immigration policy.
2. Role in Skilled Worker, Global Business Mobility and Temporary Worker visas
A valid CoS is mandatory for most work visa applications. These include:
- Skilled Worker visa – requiring the role to meet salary and skill thresholds, and in many cases to fall within eligible occupation codes.
- Health and Care Worker visa – where approved NHS bodies, social care providers, and qualifying health organisations must assign a CoS.
- Global Business Mobility routes – such as Senior or Specialist Worker, Graduate Trainee, UK Expansion Worker, Service Supplier, and Secondment Worker visas, all of which require a CoS.
- Temporary Worker visas – including the Seasonal Worker, Creative Worker, Religious Worker, Charity Worker, and Government Authorised Exchange routes.
In every case, the CoS provides the mechanism through which the sponsor declares that the role meets the visa route’s requirements and accepts responsibility for compliance in relation to that worker.
3. Digital record not paper document
Although the term “certificate” suggests a document, the CoS is entirely electronic. Once assigned, the system generates a unique reference number which the sponsor gives to the worker. The worker must use this number in their visa application.
The CoS contains details including:
- The worker’s personal information
- The job title and occupation code
- The salary being offered
- The start date of employment
- The sponsor licence details
The Home Office uses the electronic record within the SMS to cross-check information when processing the visa application. There is no physical certificate to submit.
Section Summary
The Certificate of Sponsorship is an electronic record that links a sponsor’s job offer with a migrant worker’s visa application. It is created in the Sponsor Management System and proves that the job is genuine, meets Immigration Rules, and that the employer accepts compliance duties. For Skilled Worker, Global Business Mobility, and Temporary Worker visa applicants, the CoS is the essential foundation of their application.
Section B: Types of Certificate of Sponsorship
The sponsorship framework distinguishes between two principal types of Certificate of Sponsorship: defined and undefined. Selecting the correct type is critical. Using the wrong type will delay an application, risk refusal, and may create compliance issues for the sponsor. This section explains when each type applies, how allocations work, and the position for Skilled Worker, Global Business Mobility, and Temporary Worker routes.
1. Defined CoS (Skilled Worker applying from outside the UK)
A defined CoS is required when sponsoring a Skilled Worker who will apply for entry clearance from outside the UK. Defined CoS cannot be drawn from a sponsor’s annual undefined allocation. You must submit a request through the Sponsor Management System (SMS) for each worker, setting out the job title, occupation code, salary, work location, and start date. The Home Office reviews the request and, if satisfied that the role appears eligible and credible on its face, makes a defined CoS available for assignment.
Key points to manage:
- Per-worker approval — every defined CoS is approved individually.
- Accuracy matters — occupation code, salary and work address must align with Skilled Worker requirements.
- Timing — once created, the CoS must be assigned and used in the visa application within three months.
Defined CoS requests are typically processed quickly but can take longer at peak times or where details require review. Build in contingency time and hold documentary evidence that supports your request in case UKVI asks for it.
2. Undefined CoS (in-country Skilled Worker, GBM and all Temporary Worker routes)
An undefined CoS covers:
- Skilled Workers in the UK — switching from another route, extending permission, or changing employer.
- Global Business Mobility (GBM) routes
Undefined CoS are managed through your annual allocation. Sponsors set an anticipated number during the licence year and can request an increase via the SMS with justification, for example firm recruitment plans or seasonal demand. Allocation management is a live compliance issue: running out will delay hiring, over-allocating without rationale can invite scrutiny.
For GBM, the following sub-routes require an undefined CoS:
- Senior or Specialist Worker — for intra-group transfers into senior or specialist roles.
- Graduate Trainee — for structured graduate programmes with a training role overseas.
- UK Expansion Worker — to establish a UK presence before obtaining a full trading footprint.
- Service Supplier — for contractual service suppliers and independent professionals under qualifying trade commitments.
- Secondment Worker — for workers seconded to the UK as part of a high value contract or investment.
In each GBM route the occupation code, salary or going rate requirements, group relationship and purpose of transfer must align with the specific route rules. The CoS narrative should briefly explain the group structure or contract where relevant.
3. Temporary Worker CoS (always undefined)
All Temporary Worker visas use undefined CoS. The main categories include:
- Seasonal Worker — for eligible agricultural roles sponsored by approved scheme operators.
- Creative Worker — for performers and creative team members under industry codes of practice.
- Charity Worker — for unpaid voluntary roles with registered UK charities.
- Religious Worker — for temporary religious roles that do not fit Minister of Religion.
- Government Authorised Exchange — for short-term work experience, training, research or fellowships through approved schemes.
- International Agreement — for work governed by international law or treaty obligations where applicable.
Temporary Worker routes have route-specific eligibility, maximum durations, cooling-off and supplementary work rules. The CoS must reflect the correct subcategory, role, dates and any sponsor endorsements that the route requires.
4. Choosing the correct type: practical scenarios
Use these rules of thumb to avoid avoidable refusals and rework:
- Skilled Worker applying from overseas — request and assign a defined CoS.
- Skilled Worker already in the UK — assign an undefined CoS for switches, extensions or change of employer.
- GBM or Temporary Worker — assign an undefined CoS in all cases.
- Role or location changes after assignment — consider whether withdrawal and reissue is required, and report changes via the SMS within the deadline.
Where circumstances change before the visa application is submitted, it is usually safer to withdraw the CoS and assign a new one with correct details than to proceed with inaccurate data that will not match payroll or the employment contract.
5. Allocation management and increases
Sponsors should review usage regularly against the annual undefined allocation. If you need more, request an increase through the SMS with clear evidence, such as signed offers, recruitment pipeline reports or contracts. Keep your rationale and supporting documents on file. Poor allocation hygiene is a common feature in compliance visits and may signal weak HR governance.
Remember that defined CoS are not part of the annual allocation. They must be requested per case and, once granted, assigned and used within three months.
6. Salary thresholds and occupational eligibility (cross-apply to type)
While the type of CoS depends on where the Skilled Worker applies and on the route, occupational eligibility and salary thresholds must be satisfied in every case. For Skilled Worker from 22 July 2025, headline thresholds include £41,700 general, £33,400 discounted, £31,300 transitional and £25,000 for certain Health and Care roles. The occupation code chosen on the CoS must be eligible for the route and align with the job description and contract. Mismatched codes or salaries below the threshold are frequent causes of refusal.
Section Summary
There are two CoS types. Use a defined CoS for Skilled Worker entry clearance from overseas. Use an undefined CoS for Skilled Worker in-country cases, all Global Business Mobility routes, and all Temporary Worker categories. Manage your undefined allocation proactively, request increases with evidence, and ensure occupation codes and salaries meet route rules before you assign. Correct type, accurate data and disciplined allocation control reduce refusal risk and strengthen compliance.
Section C: Applying for and Assigning a Certificate of Sponsorship
Once an organisation has been granted a sponsor licence, the next step in employing a migrant worker is to apply for and assign a Certificate of Sponsorship. This is done exclusively through the Sponsor Management System (SMS). Assigning a CoS is not simply an administrative task — it is a legally significant act that confirms the sponsor has verified the job and applicant meet Immigration Rules. Errors or misstatements can jeopardise the visa application and place the sponsor licence at risk.
1. Using the Sponsor Management System
The SMS is the Home Office’s secure online platform for sponsor licence holders. It is used to request, create and assign Certificates of Sponsorship. The key steps are:
- Request allocation — at the start of each sponsor year, employers must confirm the number of undefined CoS they anticipate requiring. For defined CoS, a separate request is needed per worker.
- Create the CoS — once allocation is in place, the sponsor logs into the SMS, inputs the worker and role details, and assigns the CoS.
- Reference number issued — on assignment, the system generates a unique reference number which is given to the worker to use in their visa application.
Only nominated users with appropriate SMS permissions can assign a CoS. Typically, a Level 1 user has full administrative access, while certain functions may also be delegated to Level 2 users. Access should be tightly controlled and managed securely.
2. Eligibility checks before assignment
Before assigning a CoS, sponsors must ensure the role and applicant meet all route requirements. This involves checking:
- Job eligibility — confirm the role is eligible under the Skilled Worker, Global Business Mobility or Temporary Worker route being used, with the correct Standard Occupational Classification (SOC) code.
- Salary compliance — verify the role meets the current salary threshold for the route. For Skilled Worker from July 2025 this is generally £41,700, with discounted rates of £33,400 for eligible roles, £31,300 transitional threshold, and £25,000 for specific Health and Care positions.
- Genuine vacancy — ensure the role is not created solely to facilitate immigration and is a genuine role within the business.
- Applicant suitability — confirm the worker has the qualifications, skills and experience required for the role.
Failure to make and document these checks risks refusal of the worker’s application and possible sponsor enforcement action. Keep evidence ready to present in the event of a Home Office compliance visit.
3. Costs, validity and timeframe
Assigning a CoS attracts costs and is subject to time limits:
- Assignment fee — £239 for Skilled Worker, Global Business Mobility and most Temporary Worker categories. A reduced £25 fee applies for Seasonal Worker and Youth Mobility Scheme routes.
- Immigration Skills Charge (ISC) — payable in addition to the CoS fee for Skilled Worker and certain Global Business Mobility roles. The ISC does not apply to Temporary Worker routes. Exemptions exist for small and charitable sponsors and for certain Health and Care roles.
- Validity period — a CoS is valid for three months from the date of assignment. The worker must apply for their visa within this period. If not used, the CoS expires and cannot be reused.
- Employment start date — the start date stated on the CoS must fall within the validity of the visa and must be realistic. Backdating is not permitted.
Sponsors must plan carefully to align CoS assignment with recruitment, visa application, and onboarding timelines. Assigning a CoS too early or with unrealistic dates can cause disruption and, in some cases, refusal.
Section Summary
The application and assignment of a CoS are managed via the Sponsor Management System. Sponsors must ensure only authorised users access the system, input accurate data, and conduct eligibility checks covering role, salary and applicant suitability. Each CoS attracts a fee, may trigger the Immigration Skills Charge, and is valid for three months. Accurate and timely handling of the process is essential to safeguard visa outcomes and maintain sponsor compliance.
Section D: Employer Duties and Compliance
Assigning a Certificate of Sponsorship is only part of the sponsorship journey. Once a CoS has been issued, the sponsor takes on a wide range of legal responsibilities that continue for the duration of the worker’s employment. These obligations are central to the UK’s sponsorship regime. Failing to meet them can trigger enforcement ranging from fines to the revocation of the sponsor licence.
1. Record-keeping and reporting duties
Sponsors must maintain detailed and up-to-date records for every sponsored worker. These must be available for inspection at any time by UK Visas and Immigration (UKVI). Typical records include:
- Copy of the worker’s passport and biometric residence permit (BRP)
- Current and historic contact details, including residential address
- Signed employment contract and job description
- Salary and payroll records
- Attendance and absence records to evidence ongoing employment
In addition to record-keeping, sponsors must report specific events to UKVI through the Sponsor Management System within 10 working days. These include:
- Failure of the worker to start their role on the stated date
- Early termination of employment
- Changes to the worker’s job title, duties, salary, or work location
- Changes in the organisation, such as mergers, demergers, or changes in key personnel
Failure to keep adequate records or to report notifiable events within the deadline is treated as a compliance breach.
2. Common errors and compliance risks
Many compliance issues arise from mistakes that are preventable with effective HR governance. The most frequent risks include:
- Assigning the wrong Standard Occupational Classification (SOC) code, causing ineligibility
- Quoting an incorrect salary that falls below the Immigration Rules threshold
- Failing to update the SMS when a worker’s role, salary, or location changes
- Assigning a CoS without verifying the worker’s qualifications or experience
- Overlooking the need to report organisational changes such as address moves or key personnel updates
These errors often lead to visa refusals and are likely to be identified during a compliance audit. They may result in penalties or adverse licence action.
3. Penalties for non-compliance
The Home Office takes sponsor compliance extremely seriously. Possible consequences include:
- Licence downgrade — from an A-rating to a B-rating, limiting the ability to assign new CoS until improvements are made.
- Suspension or revocation — in serious cases, the sponsor licence may be suspended or revoked, ending the organisation’s ability to employ sponsored workers.
- Civil penalties — fines may be issued, particularly where illegal working is identified.
- Reputational damage — loss of a sponsor licence can damage business reputation, disrupt contracts, and undermine recruitment plans.
UKVI conducts both announced and unannounced visits to check compliance. Sponsors should therefore embed ongoing compliance processes into HR and recruitment systems, not treat them as a one-off exercise.
Section Summary
Employers assigning a Certificate of Sponsorship must comply with strict record-keeping, reporting, and monitoring duties. Common errors such as incorrect SOC codes or failing to update changes can place both workers and the licence at risk. Sanctions range from downgrades to revocation and civil penalties. Continuous compliance management is essential to protect the sponsor’s ability to employ overseas workers.
FAQs
How long does a Certificate of Sponsorship last?
A Certificate of Sponsorship is valid for three months from the date it is assigned. The worker must apply for their visa using the reference number during this period. If the deadline passes, the CoS expires and cannot be reused.
Can a CoS be reused if a visa application is refused?
No. Once assigned, a CoS is locked to that application and cannot be reused. If the application is refused and the sponsor wishes to continue, a new CoS must be issued and the fee paid again.
How much does a Certificate of Sponsorship cost?
The fee is £239 for Skilled Worker, Global Business Mobility and most Temporary Worker categories. Certain short-term routes, such as the Seasonal Worker and Youth Mobility Scheme, attract a reduced £25 fee. For Skilled Worker and some GBM roles, sponsors may also need to pay the Immigration Skills Charge in addition to the CoS fee, subject to exemptions for charities and small sponsors.
What information is included in a CoS?
The CoS record includes the worker’s personal details, the job title, SOC code, salary, start and end dates, and the sponsor’s licence number. All information must match the contract and payroll records, as inconsistencies may cause refusals.
Who can assign a CoS within an organisation?
Only nominated users with SMS access rights can assign a CoS. A Level 1 user has full administrative control, while Level 2 users may be given more limited permissions, including assigning CoS where authorised. Access should be tightly controlled to prevent misuse.
Is a Certificate of Sponsorship a paper document?
No. Despite its name, a CoS is purely electronic. It is created in the Home Office’s Sponsor Management System, and the worker uses the unique reference number in their online visa application.
Section Summary
FAQs on Certificates of Sponsorship typically focus on validity, reusability, cost, information included, authorised users, and the digital format. The consistent point is that a CoS is central to a worker’s visa application and must be handled with accuracy to avoid delays and refusals.
Conclusion
The Certificate of Sponsorship is a cornerstone of the UK’s sponsored work visa framework. It is more than a simple formality: it is the mechanism through which the Home Office confirms a job offer is genuine, the role meets Immigration Rules, and the sponsoring employer accepts compliance duties. Without a valid CoS, applications under the Skilled Worker, Global Business Mobility, or Temporary Worker routes cannot proceed.
For employers, the CoS process requires careful planning, accurate record-keeping, and robust internal systems. Choosing the correct CoS type, assigning it accurately, and maintaining compliance with ongoing duties are all critical to safeguarding both visa applications and the organisation’s sponsor licence. Mistakes in salary, SOC codes, or reporting obligations can result in visa refusals, licence downgrades, or even licence revocation.
For workers, the CoS provides the vital link between their employer’s job offer and their right to apply for permission to live and work in the UK. It carries all the key information that UKVI will use to process their application.
By approaching the CoS process with diligence, employers can reduce risk, maintain compliance, and secure access to international talent. For applicants, understanding the function and requirements of a CoS is equally essential to ensuring a successful visa outcome.
Section Summary
The CoS sits at the heart of sponsorship in UK immigration law. Sponsors must manage it carefully to avoid penalties and protect their ability to employ migrant workers. Applicants must use it correctly to obtain their visa. A shared understanding of its importance ensures compliance and supports business needs and career opportunities.
Glossary
| Certificate of Sponsorship (CoS) | An electronic record created through the Sponsor Management System confirming that a licensed sponsor has offered a genuine role that meets Immigration Rules. Required for most sponsored work visas. |
| Defined CoS | A CoS required for Skilled Workers applying for entry clearance from outside the UK. Must be requested and approved individually by the Home Office before assignment. |
| Undefined CoS | A CoS used for Skilled Workers already in the UK, all Global Business Mobility routes, and all Temporary Worker visas. Sponsors receive an annual allocation to manage. |
| Sponsor Management System (SMS) | The Home Office’s secure online platform for sponsor licence holders to manage their licence, request allocations, and assign CoS. |
| Immigration Skills Charge (ISC) | A levy payable by sponsors when assigning certain CoS, including Skilled Worker roles and some Global Business Mobility categories. Exemptions apply for charities, small sponsors, and some Health and Care roles. |
| UKVI | UK Visas and Immigration, the Home Office division responsible for administering the UK’s visa system, sponsor licensing, and immigration enforcement. |
| Licence Rating | The Home Office compliance classification of a sponsor’s licence, typically an A-rating (compliant) or B-rating (requires improvement). |
Useful Links
| GOV.UK – Certificate of Sponsorship guidance | https://www.gov.uk/certificate-of-sponsorship |
| GOV.UK – Sponsor Management System guidance | https://www.gov.uk/uk-visa-sponsor-management |
| GOV.UK – Immigration Skills Charge | https://www.gov.uk/immigration-skills-charge |
| DavidsonMorris – Certificate of Sponsorship | https://www.davidsonmorris.com/certificate-of-sponsorship/ |
| Xpats.io – Certificate of Sponsorship | https://www.xpats.io/certificate-of-sponsorship/ |
| DavidsonMorris – Sponsor Licence guidance | https://www.davidsonmorris.com/sponsor-licence/ |
| Xpats.io – Sponsor Licence guidance | https://www.xpats.io/sponsor-licence/ |
