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Undefined Certificate of Sponsorship Guide
18 min read
Undefined Certificate of Sponsorship: Allocation, Use, and Limits
By SkilledJobs Editorial · Published 25 September 2026 · Last verified
An undefined certificate of sponsorship (CoS) is a type of digital certificate issued to licensed sponsors under the UK's points-based immigration system. Unlike defined certificates, which require individual Home Office approval before assignment, undefined CoS are allocated in batches to sponsors who can then assign them directly to eligible workers without seeking case-by-case permission. defined certificate of sponsorshipjobs with certificate of sponsorshipcertificate of sponsorship uk jobs
Undefined certificates of sponsorship are used primarily for Skilled Worker visa applications and certain other worker routes. They offer sponsors greater flexibility and speed when hiring overseas talent, provided the role and salary meet the Immigration Rules in force at the time of assignment.
The Home Office introduced significant changes to role eligibility requirements on 22 July 2025, reducing the number of roles eligible for sponsorship, and further updates to salary and skill thresholds came into effect from 8 April 2026. These changes apply to certificates of sponsorship assigned on or after those dates.
What Is an Undefined Certificate of Sponsorship?
An undefined certificate of sponsorship is an electronic record generated through the Home Office Sponsorship Management System (SMS). When a sponsor wishes to recruit or extend the visa of a worker in an eligible immigration route, they create and assign an undefined CoS that contains details of the job offer, salary, occupation code, and sponsor licence number.
The worker then uses the assigned CoS reference number when applying for their visa. The Home Office checks the certificate details against the Immigration Rules to determine whether the applicant meets the points and eligibility requirements for the route. Under the Skilled Worker route, the certificate forms the basis for awarding sponsorship and job offer points.
Undefined vs Defined Certificates
The key distinction between undefined and defined certificates lies in how they are allocated and the scenarios in which they are used. Undefined CoS are issued as part of an annual allocation that the sponsor receives automatically. Sponsors may assign these certificates at any time without requesting individual permission from the Home Office, provided they remain within their allocation limit.
Defined certificates, by contrast, must be requested case-by-case when a sponsor does not have undefined CoS available, or when the worker falls into a category that mandates use of a defined certificate—such as certain in-country switching scenarios or shortage occupation applications under older policy versions. The Home Office reviews each defined CoS application before granting permission to assign.
Most routine Skilled Worker sponsorships are handled through undefined certificates because they offer faster processing and greater administrative convenience. Sponsors who hold an active Worker (Skilled Worker) licence and who maintain good compliance standing typically receive and use undefined CoS for the majority of their sponsored workers.
How Undefined CoS Allocation Works
Every licensed sponsor on the Worker and Temporary Worker routes is assigned an annual allocation of undefined certificates. This allocation is set by the Home Office and reflects the sponsor's compliance history, track record, and the number of workers they have sponsored previously.
New sponsors typically receive a modest initial allocation, which may then increase over time as the sponsor demonstrates consistent compliance with sponsorship duties. The allocation renews each year, and any unused certificates at the end of the allocation period do not roll over. According to the Sponsor guidance Part 2, sponsors can view their current allocation balance and expiry date within the Sponsorship Management System.
Requesting Additional CoS
If a sponsor exhausts their allocation before the renewal date, they may apply to the Home Office for additional undefined certificates. The application is submitted through the SMS, and the Home Office will consider factors such as the sponsor's compliance record, the justification for the additional certificates, and current immigration policy priorities. There is no guarantee that additional CoS will be granted, so sponsors are encouraged to plan recruitment carefully and monitor their allocation usage.
Sponsors who require certificates urgently and have no undefined allocation remaining may need to apply for defined certificates instead, which can extend the overall timeline for worker visa applications.
Monitoring and Renewal
The Sponsorship Management System displays the sponsor's remaining undefined CoS balance at all times. Licence holders with Level 1 or Key Contact user permissions can generate allocation reports and track how many certificates have been assigned, withdrawn, or remain available. The Creating and assigning CoS manual provides step-by-step instructions on viewing allocation data and managing certificate inventory.
Allocations typically renew on the anniversary of the sponsor licence approval or at another date set by the Home Office. Sponsors are notified of their new allocation through the SMS, and the updated balance takes effect immediately upon renewal.
Eligibility and Role Requirements for Undefined CoS
Not every job offer qualifies for sponsorship under an undefined certificate. The Immigration Rules set minimum skill, salary, and occupation requirements that must be satisfied before a CoS can lawfully be assigned.
Skill Level and Occupation Codes
To sponsor a worker under the Skilled Worker route using an undefined certificate, the job must be at RQF Level 3 or above—broadly equivalent to A-level standard. The role must also appear in the Home Office list of eligible occupation codes, which are drawn from the Standard Occupational Classification (SOC) system.
From 22 July 2025, the Home Office reduced the range of eligible occupations, removing certain roles that were previously sponsorable. Sponsors must ensure the occupation code they select on the CoS matches the actual duties the worker will perform and that it remains eligible under the current rules. The Sponsor a Skilled Worker guidance contains the up-to-date list of eligible SOC codes and skill-level mappings.
Salary Thresholds
In addition to skill level, the role must meet minimum salary requirements. These thresholds are defined by the Immigration Rules and can vary depending on the occupation, the worker's circumstances, and whether any tradeable points (such as a PhD in a relevant subject) apply.
Sponsors must pay at least the higher of the general salary threshold for the route or the "going rate" for the specific occupation code. Going rates are published in the Immigration Salary List and are expressed as annual salaries for full-time employment. If the worker will be employed part-time, the sponsor must calculate a pro-rated salary threshold. For example, if the going rate for a full-time (37.5 hours per week) role is a given amount and the worker will work 30 hours per week, you multiply (30 ÷ 37.5) by the full-time going rate to determine the minimum acceptable salary.
The Immigration Rules also allow for salary reductions in limited circumstances, such as when the worker is under 26 years of age or is a new entrant to the labour market. These "new entrant" discounts are subject to strict eligibility conditions, detailed in the Skilled Worker sponsor guidance.
Genuine Vacancy Requirement
Before assigning an undefined CoS, sponsors must ensure the role represents a genuine vacancy. The Home Office defines a genuine vacancy as a real job that needs filling, for which the sponsor intends to employ the worker for the duration stated on the certificate. The role must not have been created primarily to facilitate immigration, and the sponsor must be able to demonstrate—if audited—that the duties, salary, and working conditions are legitimate.
Assigning a certificate for a non-genuine vacancy or misrepresenting job details is a serious compliance breach and can result in licence suspension or revocation. The Sponsor guidance Part 2 sets out the sponsor's duties regarding vacancy authenticity and record-keeping.
Creating and Assigning Undefined CoS in the SMS
Sponsors create and assign undefined certificates through the Sponsorship Management System, an online portal maintained by UK Visas and Immigration. Access to the SMS is restricted to users with active sponsorship roles (typically Key Contact, Level 1, or Level 2 users, depending on the function).
Step-by-Step Assignment Process
Log in to the SMS using the sponsor's login credentials. Navigate to the section for creating a new certificate of sponsorship.
Select the immigration route (for example, "Worker – Skilled Worker") and choose "Undefined" as the certificate type.
Enter the worker's personal details, including full name, date of birth, nationality, and passport number. The system will check whether the worker already holds a current visa or has been sponsored previously.
Specify the job details: occupation code (SOC), job title, brief description of duties, and start date. The occupation code must be eligible under the Skilled Worker rules and correspond to the work actually being offered.
Enter salary information: annual gross salary, working hours per week, and any allowances that form part of the salary for Immigration Rules purposes. The SMS will validate that the salary meets the applicable threshold for the selected occupation code and route.
Confirm sponsor licence details and the workplace address where the worker will be based. If the role involves multiple sites, sponsors must ensure they have registered all relevant locations with the Home Office.
Review and assign the CoS. Once assigned, the certificate is deducted from the sponsor's undefined allocation, and a unique CoS reference number is generated. This number must be provided to the worker for their visa application.
The Creating and assigning CoS manual provides detailed screenshots and field-by-field instructions for each stage of the assignment process.
Amending or Withdrawing a CoS
If the sponsor identifies an error in the certificate after assignment, or if the job offer is withdrawn before the worker applies for their visa, the sponsor can request to withdraw or amend the CoS through the SMS. Withdrawal returns the certificate to the sponsor's allocation, provided the worker has not yet submitted their visa application.
Changes to certain details—such as salary or job title—may require the certificate to be withdrawn and a new one assigned. Minor corrections, such as a misspelled name, can sometimes be amended without full withdrawal. Sponsors should consult the Sponsor guidance Part 2 or contact the sponsor helpline if unsure whether an amendment is permitted.
Priority Change of Circumstance Service
In urgent cases where a sponsor needs to amend a certificate quickly, the Home Office offers a priority change of circumstance service. This paid service is designed for time-sensitive scenarios, such as correcting errors that would otherwise delay a worker's visa application. Standard processing times and fees apply; sponsors must submit the request through the SMS and pay the relevant fee online.
Compliance and Record-Keeping Obligations
Assigning an undefined certificate of sponsorship creates ongoing compliance duties for the sponsor. These obligations continue throughout the worker's employment and are a condition of maintaining the sponsor licence.
Reporting Duties
Sponsors must report certain events to the Home Office within specified time frames. Reportable events include the worker's failure to turn up for their first day of work, any significant changes to job duties or salary, long-term absence, and termination of employment. Reporting is done through the SMS, and timely reporting is a key compliance metric monitored by the Home Office during audits.
The Sponsor guidance Part 2 lists all reportable events and the deadlines for each. Failure to report can lead to a downgrade of the sponsor's compliance rating, civil penalties, or licence action.
Document Retention
Sponsors must keep copies of documents that evidence the worker's right to work, the terms of their employment, and compliance with the Immigration Rules. These include the employment contract, payslips, proof that the salary stated on the CoS is being paid, and records of any absence or changes in circumstances.
Document retention requirements are set out in the sponsor guidance, and sponsors should maintain organised records for at least the duration of the worker's sponsorship plus any period specified by the Home Office. During a compliance visit or audit, UKVI officers will request to see these documents, and missing or incomplete records can result in a downgrade or suspension of the licence.
Maintaining Accurate CoS Data
The information entered on the undefined certificate must be accurate and must reflect the genuine terms of employment. If circumstances change after the CoS is assigned—for example, if the salary increases or the role title is updated—the sponsor must assess whether a new CoS is required or whether the change can be managed as a reportable event.
Deliberately providing false information on a certificate, or knowingly sponsoring a worker for a role they will not actually perform, constitutes immigration fraud and can lead to criminal prosecution as well as licence revocation.
Common Scenarios and Use Cases
Undefined certificates are most commonly used in the following situations:
Recruiting a new Skilled Worker from overseas: The sponsor assigns an undefined CoS to an overseas candidate who has accepted a job offer. The candidate applies for entry clearance using the CoS reference number.
Extending a current Skilled Worker's visa: When a sponsored worker's visa is due to expire and they wish to remain with the same employer, the sponsor assigns a new undefined CoS to support the extension application.
Switching from another visa route: A worker in the UK on a different visa category (for example, a Graduate visa) applies to switch into the Skilled Worker route. The sponsor assigns an undefined CoS, and the worker applies to UK Visas and Immigration to change their immigration status.
Changing employer within the Skilled Worker route: A worker currently sponsored by another employer applies to switch to a new sponsor. The new employer assigns an undefined CoS, and the worker submits a change-of-sponsorship application.
In each of these scenarios, the sponsor must confirm that the role meets the skill and salary thresholds in force at the time of CoS assignment. The effective date of the Immigration Rules changes is important: updates that took effect from 8 April 2026 apply to certificates assigned on or after that date, regardless of when the licence was issued or the worker's application was submitted.
When a Defined CoS Is Required Instead
Although undefined certificates are the default choice for most sponsorships, there are situations where a defined CoS must be used:
The sponsor has exhausted their undefined allocation and has not been granted additional certificates.
The worker is applying under a category or concession that requires individual Home Office approval.
The role falls into a niche or complex scenario not covered by the standard undefined allocation framework.
Because defined CoS applications require case-by-case Home Office review, they take longer to process. Sponsors should plan ahead and avoid relying on defined certificates for routine hires if undefined allocation is available.
The Sponsor guidance Part 2 provides detailed guidance on when a defined certificate is mandatory and how to apply through the SMS.
Impact of Recent Policy Changes
The Immigration Rules governing Skilled Worker sponsorship have been updated multiple times in recent years. Two sets of changes are particularly relevant to sponsors assigning undefined certificates in 2026:
July 2025 Occupation Code Changes
On 22 July 2025, the Home Office removed a number of occupation codes from the list of roles eligible for Skilled Worker sponsorship. Sponsors who had previously hired workers in those roles can no longer assign new certificates for the same occupation code unless the role has been reclassified or meets alternative eligibility criteria. The updated eligible occupation list is published in the Skilled Worker sponsor guidance.
April 2026 Salary and Skill Threshold Updates
Further changes to salary and skill requirements came into effect from 8 April 2026. These updates apply to certificates of sponsorship assigned on or after that date. Sponsors must ensure they are using the correct thresholds when creating new undefined CoS and must not rely on older policy guidance or threshold figures published before April 2026.
The Sponsor a Skilled Worker version 04/26 guidance document reflects the current rules and should be the primary reference for all salary and eligibility questions.
Practical Tips for Sponsors
Monitor your allocation balance regularly through the SMS to avoid running out of undefined CoS mid-recruitment cycle.
Plan recruitment timelines to account for the annual allocation renewal date. If a large intake of workers is expected, consider requesting additional CoS in advance rather than waiting until the allocation is depleted.
Double-check occupation codes and salary calculations before assigning a certificate. Errors discovered after the worker applies for their visa can be difficult and expensive to correct.
Keep the SMS user list up to date. Ensure that only authorised personnel have access to create and assign certificates, and remove users who have left the organisation or changed roles.
Maintain clear internal records of every CoS assigned, including the job offer, employment contract, and evidence that the role meets Immigration Rules requirements. These records are essential during Home Office compliance audits.
Seek specialist advice if uncertain about eligibility, salary calculations, or whether a defined certificate is required. Immigration rules are complex, and incorrect CoS assignment can delay visa applications and damage the sponsor's compliance rating.
Frequently Asked Questions
Can I assign an undefined CoS to a worker who is already in the UK?
Yes, provided the worker is eligible to switch into or extend their stay under the Skilled Worker route. The certificate assignment process is the same whether the worker is overseas or in the UK, but the visa application route and fees will differ.
What happens if I assign a CoS and the worker does not use it?
If the worker does not submit a visa application, or if the offer is withdrawn before the application is made, the sponsor can withdraw the certificate through the SMS. The unused CoS will be returned to the sponsor's allocation, provided the withdrawal is completed before the worker's application is processed.
How long is an undefined CoS valid?
Once assigned, the certificate remains valid for three months from the intended start date entered on the CoS. The worker must submit their visa application within this validity window. If the certificate expires unused, it cannot be reinstated and a new CoS must be assigned.
Can I amend the salary on an assigned CoS?
Minor increases to salary can sometimes be reported as a change of circumstances after the visa is granted. However, if the salary needs to be reduced or significantly amended before the visa application is submitted, the sponsor should withdraw the original CoS and assign a new certificate with the correct details. Consult the Sponsor guidance Part 2 or the SMS helpline for specific advice.
Do I need to pay a fee to assign an undefined CoS?
There is no Home Office fee to assign an undefined certificate from your existing allocation. However, sponsors must pay the Immigration Skills Charge when the worker's visa application is granted. The charge amount depends on the size of the sponsor organisation and the length of the visa. Defined CoS applications, by contrast, carry an application fee.
What is the Immigration Skills Charge, and when is it due?
The Immigration Skills Charge is a fee that sponsors must pay for each sponsored worker. The charge is calculated based on whether the sponsor is a small or large organisation and the duration of the worker's visa. Payment is made when the worker's visa application is approved, not at the point of CoS assignment. The Sponsor guidance Part 2 provides the current charge rates and exemptions.
Summary
Undefined certificates of sponsorship are the primary mechanism through which UK employers sponsor Skilled Workers and other eligible migrants. They offer speed, flexibility, and administrative convenience, but sponsors must ensure every certificate is assigned in line with current Immigration Rules and that all skill, salary, and occupation requirements are met.
Understanding your annual allocation, monitoring usage, and maintaining robust compliance records are essential to successful sponsorship. As policy evolves—most recently with the changes introduced in July 2025 and April 2026—sponsors must stay informed and adapt their processes to reflect the latest guidance published on GOV.UK.
By following the procedures set out in the official sponsor guidance and using the Sponsorship Management System correctly, employers can assign undefined CoS with confidence and support their overseas hires in obtaining the visas they need to work legally in the UK.
