For UK businesses employing migrant workers, understanding sponsorship obligations is essential. One of the most important components of the sponsorship framework is the Certificate of Sponsorship (CoS). For employers dealing with workers who are already in the UK, the Undefined Certificate of Sponsorship (UCoS) is particularly relevant. Proper use of Undefined Certificate of Sponsorship (UCoS) enables businesses to retain skilled workers, manage visa extensions, and support employees switching visa categories, while remaining compliant with Home Office requirements.
This guide provides a detailed overview of Undefined Certificate of Sponsorship (UCoS), explaining how they work, how they are allocated, and what business owners must do to manage them correctly.
Understanding Certificates of Sponsorship
A Certificate of Sponsorship (CoS) is an electronic record generated through the Home Office Sponsorship Management System (SMS). It confirms that a licensed UK employer is sponsoring a migrant worker for a specific role. Although referred to as a certificate, it is not a physical document. Instead, it is a reference number that the worker uses when submitting their visa application.
There are two types of Certificates of Sponsorship: Defined and Undefined. Importantly, the defined and undefined distinction applies only to the Skilled Worker route. A Defined CoS is used for Skilled Worker applicants applying from outside the UK. An Undefined CoS is used for Skilled Workers applying from within the UK and for applicants on all other sponsored work routes. Understanding this distinction is critical, as assigning the wrong type of CoS can lead to visa refusals and compliance action.
What Is an Undefined Certificate of Sponsorship (UCoS)?
An Undefined Certificate of Sponsorship (UCoS) is used when a migrant worker is already present in the UK and is applying to switch visa categories, extend their existing permission, or change employment.
Undefined Certificates of Sponsorship are also used for all other sponsored work routes, including Global Business Mobility and Temporary Worker routes. Unlike the Skilled Worker route, these routes do not operate a separate defined request process for overseas applicants.
Unlike a Defined Certificate of Sponsorship, employers do not need to submit an individual request to the Home Office for each Undefined Certificate of Sponsorship (UCoS) before assignment. Instead, the Home Office provides sponsors with an annual allocation of Undefined CoS, which can be assigned as required during the allocation year, provided the sponsor has sufficient certificates available.If the allocation finishes during the year, additional allocations can be applied.
Who Can Use an Undefined CoS?
Undefined CoS can only be used by organisations that hold a valid sponsor licence and have been granted an annual allocation by the Home Office. The sponsored role must meet the relevant skill and salary thresholds under the Immigration Rules, and the worker must be eligible to apply from within the UK under the applicable route.
When assessing allocations, the Home Office considers factors such as the size of the business, previous sponsorship activity, compliance history, and anticipated recruitment needs. Employers must therefore be able to justify their use of Undefined CoS at all times.
Allocation and Management of Undefined CoS
When applying for a sponsor licence, businesses are required to estimate how many Undefined Certificate of Sponsorship (UCoS) they will need in their first year. This estimate must be realistic and supported by evidence if requested. Once approved, the allocation appears in the organisation’s SMS account and remains valid for 12 months.
Unused Undefined Certificate of Sponsorship (UCoS) cannot be carried forward into the next allocation year. For A-rated sponsors, the Home Office may automatically renew allocations based on previous usage. If an employer exhausts their allocation or anticipates increased recruitment, they must submit a request for additional Undefined CoS through the SMS.
Processing times for additional allocation requests vary and can take several weeks (up to 18 weeks), particularly during busy periods. Although a priority service is available, availability is limited. Therefore, it is recommended to begin the renewal or extension process as early as possible to avoid delays.
Regular monitoring of CoS usage is essential to prevent recruitment delays and ensure compliance.
Step-by-Step Process: Assigning an Undefined Certificate of Sponsorship
The Undefined Certificate of Sponsorship (UCoS) process must be handled carefully, as each assignment is treated by the Home Office as a formal legal declaration. Errors at any stage can lead to visa refusals, delays, or sponsor licence compliance action. The steps below outline the correct process from allocation to visa application.
Step 1: Hold a Valid Sponsor Licence
Before an Undefined CoS can be used, the business must hold a valid sponsor licence in the relevant category (such as Skilled Worker or Global Business Mobility). Only A-rated sponsors can freely assign Certificates of Sponsorship. If a licence is downgraded or suspended, CoS assignment will be restricted.
Step 2: Check Your Annual Undefined CoS Allocation
Once a sponsor licence is granted, the Home Office provides an annual allocation of Undefined CoS.
- Log in to the Sponsorship Management System (SMS).
- Review the number of Undefined CoS currently available under your licence.
- Ensure your allocation covers both new recruitment and upcoming visa extensions for existing sponsored workers.
If your allocation is insufficient, you must request additional Undefined CoS before proceeding.
Step 3: Request Additional Undefined CoS (If Required)
If you do not have enough Undefined CoS to meet your needs:
- Submit a request through the SMS under “Request additional CoS allocation”.
- Provide a business justification explaining how many certificates are required and why (for example, anticipated recruitment or visa extensions over the next 12 months).
- Wait for Home Office approval. Processing times can take several weeks unless the priority service is used.
You cannot assign a CoS until the additional allocation is approved and visible in the SMS.
Step 4: Confirm Worker Eligibility
Before assigning an Undefined Certificate of Sponsorship (UCoS), confirm that the worker meets all immigration requirements:
- The worker must already be in the UK and eligible to apply from within the country.
- The visa route must permit switching or extension.
- The worker must meet English language, financial, and immigration history requirements where applicable.
Assigning a CoS to an ineligible worker risks refusal and compliance scrutiny.
Step 5: Confirm Role Eligibility
The sponsored role must meet Home Office criteria before a CoS is assigned:
- The correct occupation (SOC) code must be selected.
- The salary must meet the applicable minimum threshold for the role and worker category.
- The role must be genuine, skilled, and consistent with the business’s activities.
Many refusals arise from incorrect SOC codes or salary miscalculations.
Step 6: Finalise Employment Details
Before assigning the CoS, ensure all employment terms are agreed and documented:
- Job title and duties
- Salary and working hours
- Start date and end date
- Work location (including hybrid or multi-site arrangements)
Assigning a CoS before contracts are finalised increases the risk of errors and wasted certificates.
Step 7: Assign the Undefined CoS via the SMS
Once all checks are complete:
- Log in to the SMS.
- Select “Assign CoS” and choose an Undefined CoS.
- Enter all required job and worker information accurately.
- Review the information carefully before submission.
Any incorrect information entered at this stage may invalidate the CoS.
Step 8: Pay the Required Fees
At the point of assignment, the employer must pay:
- The CoS assignment fee.
- The Immigration Skills Charge, if applicable.
These costs must be paid by the employer and must not be recovered from the worker.
Step 9: Worker Submits Visa Application
After the CoS is assigned:
- The worker uses the CoS reference number to submit their visa application.
- The application must be submitted within three months of CoS assignment.
- The visa application cannot be submitted more than three months before the job start date.
If the worker fails to apply in time, the CoS expires and cannot be reused.
Step 10: Record-Keeping and Ongoing Compliance
Once the CoS is assigned, compliance obligations continue:
- Maintain a full compliance file for the worker, including contracts, job descriptions, and salary evidence.
- Track CoS usage and cancel unused or withdrawn certificates promptly via the SMS.
- Report any relevant changes (such as job role or work location changes) in line with sponsor duties.
Failure to maintain accurate records may trigger Home Office audits or enforcement action.
Fees and Associated Costs
Each time an Undefined Certificate of Sponsorship is assigned, a fee must be paid to the Home Office. For the Skilled Worker and Global Business Mobility routes, the CoS assignment fee is £525 per certificate. For Temporary Worker routes, the fee is £55.
In many cases, employers must also pay the Immigration Skills Charge. This charge is calculated per year of sponsorship and varies depending on the size of the organisation. It is based on the total length of sponsorship and must be paid in full at the point of CoS assignment, unless an exemption applies. Employers are not permitted to recover sponsorship-related costs from the worker.
Compliance Responsibilities for Business Owners
Assigning an Undefined CoS creates ongoing compliance obligations. All information entered into the SMS must be accurate and supported by appropriate documentation. The Home Office may cross-check details against HMRC records and may conduct compliance audits without prior notice.
Employers must maintain comprehensive records for each sponsored worker, including job descriptions, salary details, employment contracts, and evidence that the role is genuine and sustainable. Weak record-keeping or repeated errors may result in sponsor licence downgrading, suspension, or revocation.
Common Mistakes to Avoid
Many sponsorship problems arise from avoidable mistakes. These include selecting the wrong occupation code, entering an incorrect salary, assigning the wrong type of CoS, or issuing a certificate before employment details are finalised. Timing errors are also common, as a CoS expires after three months if it is not used.
Failing to cancel unused or withdrawn certificates can raise compliance concerns during audits. Employers should also be cautious about recent changes to salary thresholds and occupation codes, as outdated assumptions can lead to refusals.
How City Legal Can Help
Managing Undefined Certificates of Sponsorship involves significant legal and compliance responsibilities, and errors can expose businesses to visa refusals or sponsor licence action. City Legal supports employers by advising on Undefined Certificate of Sponsorship (UCoS) planning, allocation forecasting, and eligibility assessments, ensuring that both the role and the worker meet the current Immigration Rules before any certificate is assigned. This includes guidance on occupation codes, salary thresholds, and justification for additional CoS allocations, helping businesses avoid common technical pitfalls.
City Legal also provides practical support during and after the CoS assignment process by reviewing information entered into the Sponsorship Management System and advising on record-keeping and ongoing sponsor duties. By helping businesses implement compliant internal processes and respond effectively to Home Office scrutiny, City Legal enables employers to manage Undefined Certificate of Sponsorship (UCoS) of Sponsorship with confidence while protecting their sponsor licence and workforce continuity.
Final Thoughts
Undefined Certificate of Sponsorship (UCoS) are a crucial element of the UK’s sponsorship system for workers already in the country. While the process may appear administrative, each assignment carries legal and compliance significance. Business owners who plan carefully, monitor allocations, and maintain accurate records are far better placed to manage sponsorship effectively.
A structured and compliant approach to Undefined Certificate of Sponsorship (UCoS) not only supports workforce stability but also protects the sponsor licence, ensuring long-term access to skilled talent within the UK.
