DCoS & Undefined Certificates of Sponsorship Guide

Section A: What is a Certificate of Sponsorship (CoS)?

One of the mandatory requirements of sponsored work routes such as the Skilled Worker visa and Global Business Mobility visas is that the applicant has a valid Certificate of Sponsorship (CoS) from a licensed employer. The CoS is an electronic record with a unique reference number that links a specific job offer to a specific visa applicant.

In practical terms, a CoS is a way for a UK employer (the sponsor) to confirm to the Home Office that they are offering a genuine, eligible job to a non-UK worker who meets the requirements of the relevant visa route, including skill level and salary.

For the worker, the CoS acts as official proof that they have a confirmed job offer from a UK employer with a valid sponsor licence. The CoS is then used by the worker to make their visa application.

1. Which visas require a Certificate of Sponsorship?

Workers being employed under sponsored work visa categories, such as the Skilled Worker visa and the sponsored stage of the Scale Up visa, require a CoS to be allocated by their UK employer. The cost of assigning a CoS depends on the type of licence the employer has:

2. Types of CoS

Reform of the UK points-based immigration system saw the Skilled Worker route replace the Tier 2 (General) visa, and the two types of CoS were also revised. Restricted and unrestricted CoS are no longer issued and were replaced by Defined and Undefined CoS.

A Defined CoS (DCoS) is required only when the worker is applying from outside the UK under the Skilled Worker route.

An Undefined CoS is used for workers already in the UK, such as those switching visa routes or extending their permission, and for all other sponsored visa routes whether the applicant is applying in the UK or overseas. Employers usually receive an annual allocation of Undefined CoS, which must be requested with supporting evidence when applying for a sponsor licence or through later allocation requests.

The sponsor has to assign the correct type of CoS to each worker it wants to sponsor under the points-based system. UKVI operates an online Sponsor Management System (SMS). The SMS is used by sponsors to apply for and manage their licence. This includes requesting and allocating Certificates of Sponsorship to sponsored visa workers.

The worker then uses the CoS to make their visa application to the Home Office. The worker must apply for their visa within 3 months of the CoS being assigned to them, and no earlier than 3 months before the start date of their job. For Defined CoS, once approved by the Home Office, the certificate appears in the sponsor’s SMS account and must be assigned within 90 days.

3. CoS allocations

Once UKVI allocates Undefined CoS, the sponsor has 12 months (the “CoS year”) to use them. Sponsors can view their current allocation at any time by logging into their SMS account.

For most sponsors, the annual CoS allocation runs for 12 months from the date the sponsor licence was granted and, in subsequent years, 12 months from the date an allocation renewal request is approved.

It is important to monitor the CoS allocation carefully, particularly if you have recruitment plans that depend on sufficient CoS availability.

A-rated sponsors on eligible routes may receive an automatic annual allocation, but some routes require a manual request. For example, routes such as Seasonal Worker, Secondment Worker, Service Supplier and UK Expansion Worker are not eligible for automatic renewal and must submit a manual allocation request.

Unused certificates are removed from the SMS at the end of the CoS year; they cannot be carried forward. If your business needs change and your organisation requires more CoS than your automatic allocation allows, you will need to request an increase through the SMS, providing reasons and supporting information.

Section B: What is a Defined CoS (DCoS)?

For Skilled Worker visa applications made from outside the UK, known as ‘entry clearance’, sponsors will need to apply for a Defined CoS. This type of CoS must be requested and approved by the Home Office before it can be assigned to a worker. Importantly, the organisation must hold an A-rated sponsor licence in order to be able to assign a Defined CoS.

DCoS requests are made through the SMS. Applications are typically processed within a working day, unless further information is requested in relation to the role, the recruitment process or the job candidate. Once a DCoS has been granted, the details cannot be amended. If the information provided is incorrect, the certificate must normally be withdrawn and a new request submitted. Sponsors cannot “edit” a granted DCoS, although minor notes can be added before assignment.

If the individual is seeking to trade points, for example to rely on a reduced salary threshold, the CoS will need to explain how those points are claimed, such as whether the role is on the Immigration Salary List, or the worker is a new entrant.

Once approved, the certificate appears in the sponsor’s SMS account and must be assigned to the named worker within 90 days.

1. DCoS Requests: increased Home Office scrutiny

Employers applying for DCoSs via the SMS have observed a significant uplift in requests for supplementary information from the Home Office. These requests often include:

• Business-specific justifications: detailed explanations of why additional sponsored workers are needed, specific to the organisation.
• Comprehensive job descriptions: full outlines of the duties associated with the roles being filled.
• Evidence of genuine vacancies: official contracts or agreements demonstrating guaranteed work, including relevant clauses highlighted.
• Operational context: hierarchy charts identifying organisational roles and a breakdown of existing and vacant positions, including those held by sponsored workers.
• Employment records: staff rotas and employment contracts for existing workers in similar roles.
• Location-specific information: clarification of where sponsored workers will be employed within the UK.
• Industry-specific compliance evidence: for care providers, CQC registration and detailed service agreements, among other documents.

These requirements are particularly prevalent in high-risk industries, such as care homes, which often face challenges in providing some of the requested evidence. While the Home Office has not officially articulated the reasons for this shift, several factors are likely at play, such as wider policy objectives and the government push to reduce net migration, reports of sponsorship visa abuse and breaches of compliance obligations in high-risk sectors, and a surge in sponsor licence holders leading to closer scrutiny of applications.

What is clear is that this new approach is placing a significant administrative burden on employers. In particular, additional information requests can lengthen the application process, potentially affecting recruitment timelines. In some cases, sponsors struggle to meet evidentiary requirements, leading to rejected applications.

We are advising clients to take a fully holistic approach by providing extensive supporting evidence to reduce the potential for information requests.

Section C: What is an Undefined CoS?

An Undefined Certificate of Sponsorship (UDCoS) is used when the worker is already in the United Kingdom and is either switching visa category, applying for a visa extension or changing job. Undefined CoS are also used for applications under other visa routes, including the Global Business Mobility routes, whether the applicant is applying from within the UK or overseas.

When an organisation makes their sponsor licence application, they submit a request for Undefined CoS. The application will need to include evidence to support the requested number, although there is no overall cap on the number of Undefined CoS that may be assigned, provided the workers are eligible under the visa route and the sponsor pays the fee to assign each CoS.

UKVI then decides the annual allocation based on factors such as the business’s size and compliance history. Employers can view the number of available Undefined CoS at any time through their SMS account. If the sponsor does not have enough Undefined CoS to meet recruitment needs, it will be necessary to submit a request for additional allocation through the SMS. When making the request, the sponsor must provide details of the number of additional Undefined CoS required and explain the reasons, for example to cover anticipated recruitment activity over the next 12 months.

Once the request has been submitted, the sponsor must wait for Home Office approval. Processing times for additional Undefined CoS requests vary and can be lengthy. A priority service is available for a fee, which provides a decision within 5 working days if the request qualifies.

After the Home Office approves the request and the additional Undefined CoS are available in the SMS account, the sponsor can proceed to assign a CoS to a worker. When assigning the CoS, the information submitted must be correct and accurate, or the employer risks enforcement action. Once the information is complete, the CoS must be formally submitted through the SMS.

1. Undefined CoS for UK Expansion Workers

Organisations that have been given a provisional licence rating under the UK Expansion Worker route will only be permitted to assign one CoS. This CoS must be assigned to the organisation’s Authorising Officer to enable them to travel to the UK.

Once the Authorising Officer’s visa has been granted, the sponsor licence can be upgraded to an A-rating, enabling the organisation to request up to four further CoS through the SMS.

Section D: How to Assign a CoS

The sponsor must assign the correct certificate type to each worker, since assigning the wrong type or providing incorrect information can lead to visa refusals or compliance action. Sponsors must hold an A-rated licence to be able to assign a Defined CoS, and caseworkers will confirm the licence status when processing Skilled Worker applications.

Before assigning a certificate, sponsors should ensure the role itself is eligible under the Immigration Rules. This means checking that the occupation code is correct, the salary meets the appropriate threshold, and any points being traded (for example for shortage roles or new entrants) are clearly identified and justified. Many refusals stem from simple mistakes in coding or misjudging the right salary band.

The CoS record must include accurate details such as job title, occupation code, salary, hours, employment start and end dates, and work location. Assignment should only take place once recruitment, contracts and payroll details are finalised. Assigning a CoS prematurely, before terms are settled, creates a high risk of errors and wasted certificates.

Each CoS assignment is treated by the Home Office as a formal legal declaration. If details are incorrect, it is not only the worker’s visa that may be refused but the sponsor licence itself can be scrutinised for wider compliance failings. Employers should treat the assignment process as part of their compliance programme, with clear checks in place.

A fee is payable each time a CoS is assigned. Worker routes (including Skilled Worker and Senior or Specialist Worker) cost £525 per certificate; Temporary Worker routes cost £55 per certificate; and the International Sportsperson route costs £525 for assignments over 12 months or £55 for 12 months or less. Sponsors must pay the CoS fee and must not recoup sponsorship-related fees (e.g., CoS, visa, ISC) from the worker. If sponsoring a Skilled Worker or Senior or Specialist Worker, the sponsor may also need to pay the Immigration Skills Charge. Employers should budget for the full cost of sponsorship, including the CoS fee, Immigration Skills Charge and visa fees, as these costs quickly add up.

The process to assign a CoS depends on whether it is a Defined CoS or an Undefined CoS.

1. Defined Certificate of Sponsorship (DCoS)

A Defined CoS is required when a worker is applying from outside the UK under the Skilled Worker visa route.
Use your organisation’s credentials to access the SMS provided by the Home Office when you were granted a sponsor licence. Navigate to the ‘Create and Assign CoS’ section. From the menu, select “Defined CoS Requests” under the Skilled Worker route. You will not be able to assign a Defined CoS until the request has been approved by the Home Office.
Submit a Defined CoS request by completing the online form with the required information about the job and the worker, including:

• Job title and occupation code
• Salary details
• Work start date and end date
• Work location
• Confirmation that the job meets the Skilled Worker requirements

You then submit the request and wait for a decision.
In some cases, the Home Office may request evidence to show the vacancy is genuine, especially if the job role or salary appears borderline or unusual. Employers must be ready to respond quickly, with recruitment records, contracts and business justifications available.
Most Defined CoS requests are processed within one working day, but delays can occur if further checks are needed. You will receive a notification via SMS once the request is approved. Once granted, a Defined CoS cannot be amended. If errors are made, the certificate will usually need to be withdrawn and a new request submitted. Employers should therefore build in a second internal check before the request is sent.
Once the request is approved, you can assign the Defined CoS to the named individual. You must include accurate personal and job information, as this will be used by the Home Office to assess the visa application.

2. Undefined Certificate of Sponsorship (UDCoS)

An Undefined CoS is used when the worker is already in the UK and switching visa category, or applying for an extension or change of employment. It is also used for other sponsored work routes, such as Global Business Mobility routes.
To request or use an Undefined CoS, you should first check your annual CoS allocation. When you receive your sponsor licence, the Home Office provides an annual allocation of Undefined CoS. You can view your available allocation in your SMS account. If you do not have enough in your allocation, you must submit a request for additional Undefined CoS. To do this:

• Log in to the SMS
• Navigate to “Request additional CoS allocation”
• Provide details about the number of CoS needed and the reasons (e.g. expected recruitment over the next year)

Requests for additional Undefined CoS can take several weeks. If timescales are pressing, employers can use the post-licence priority service, which considers eligible requests within 5 working days for a fee of £200. This service has daily limits, so requests must be made early in the morning to maximise chances of success.
Once you have a sufficient number of Undefined CoS in your SMS account, you can assign one to a worker. Enter the required job and applicant information and submit the assignment. To avoid errors, sponsors should implement an internal workflow where HR, finance and the Level 1 user all review the information before submission.

3. Refused CoS request

The Home Office will write to you to notify if your request has been successful or otherwise.
If a request for a Defined or Undefined CoS is refused, the sponsor can usually reapply, but the decision may highlight compliance concerns that should be addressed before making a new request. Cooling-off periods or bans do not apply to refused CoS requests, although they can apply in cases of sponsor licence refusal or revocation. Sponsors should therefore record the reasons for refusal, review their internal compliance processes, and take remedial action before submitting a new request.

Section E: Common CoS risks for employers

Assigning a Certificate of Sponsorship (CoS) carries legal and compliance responsibilities for UK employers. If handled incorrectly, it can lead to visa delays, refusals, sponsor licence action or Home Office investigations. Employers need to treat every CoS assignment as a compliance event in its own right, not just an administrative step. Below are the most common risks and how to manage them effectively.

1. Be aware of the three-month validity period

Once a Certificate of Sponsorship has been assigned, it is valid for only three months. The visa applicant must submit their application within this timeframe and no earlier than three months before the job start date. If the deadline is missed, the CoS expires and cannot be reused. Employers should therefore align CoS assignment dates with confirmed recruitment timelines and monitor expiry dates closely.

2. Don’t forget the Immigration Skills Charge

If the Immigration Skills Charge (ISC) applies, it must be paid when assigning the CoS. Failure to do so may result in the visa being rejected or delayed. The ISC is charged in addition to the CoS fee, and exemptions are limited. Finance teams should be involved early so that funds are available on the date of assignment.

3. Maintain accurate and complete records

For every CoS you assign, you must keep detailed records. This includes the job description, salary details, employment contract, and evidence of the recruitment process. These records must be readily available if the Home Office inspects your organisation. Weak record-keeping is one of the most common reasons for compliance breaches. Employers should keep a CoS compliance file for each sponsored worker, updated throughout their employment.

4. Treat CoS responsibilities as legal obligations

Incorrect, careless, or non-compliant use of the CoS system can trigger serious consequences. These include Home Office audits, potential enforcement action, and suspension or revocation of your sponsor licence. Sponsors should implement a dual-review process so that no CoS is assigned without at least two sets of eyes confirming the details.

5. Not meeting salary thresholds or job requirements

Assigning a CoS for a job that does not meet the required salary or skill threshold will almost certainly lead to visa refusal. Each eligible occupation has specific salary requirements, with different thresholds for experienced workers, shortage occupations and new entrants. Employers must double-check that the SOC code selected is correct and that the salary matches the rules in force at the time of assignment. Salary compliance is now often cross-checked by the Home Office against HMRC data, so errors carry increased risk.

6. Inadequate or inaccurate supporting evidence

If the Home Office doubts whether a job offer is genuine, they may request additional evidence or reject the visa application outright. This risk is particularly high in sectors flagged as “high-risk”, such as health and social care. Employers should be ready to produce recruitment records, contracts, payslips of comparable roles, and organisational charts to show that the vacancy is real and sustainable. Keep this evidence on file before assigning the CoS.

7. Incorrect information on the CoS

Errors such as the wrong job title, working hours, job location or start date can invalidate the CoS and cause the visa application to fail. For Defined CoS, these mistakes mean withdrawing the certificate and submitting a new request, which delays recruitment and increases costs. Employers should put in place an internal checklist and require all fields to be cross-checked against the employment contract before submission.

8. Timing and sequencing problems

Because a CoS can only be used within three months of assignment, poor timing is a recurring issue. Assigning too early risks expiry, while assigning too late can push back a worker’s visa application and start date. Employers should plan backwards from the intended start date, factoring in visa processing times, priority service availability and travel logistics. A project plan for each recruitment is the safest approach.

9. Failure to track and record CoS use

Employers must be able to account for each CoS assigned. Failing to cancel unused CoS or repeatedly assigning certificates that are not taken up creates red flags during compliance checks. Sponsors should track each CoS in a central register, noting the worker’s name, visa outcome, and any cancellations. Cancel unused CoS promptly via the SMS.

10. Risk of triggering a compliance visit

Suspicious or inaccurate CoS assignments can trigger a compliance audit by the Home Office. Audits can lead to downgrading, suspension or even revocation of the sponsor licence. Employers should treat every CoS assignment as a compliance event and maintain a complete evidentiary trail to demonstrate genuine need and accurate record-keeping.

Section F: Summary

Certificates of Sponsorship sit at the centre of the UK’s sponsored work visa system. They are not just administrative forms but formal declarations by employers to the Home Office that the job is genuine, eligible and meets the rules in force at the time of assignment. For Defined CoS, sponsors must request approval for each case and be ready to supply evidence on demand. For Undefined CoS, sponsors need to manage allocations carefully, ensuring that requests for additional certificates are justified and supported.

The rules on validity and timing are strict. A CoS must be used within three months of assignment, and premature assignment often causes problems when start dates move or applications are delayed. Each assignment also carries costs, from the CoS fee to the Immigration Skills Charge, which employers must budget for in advance. Mistakes, whether in coding, salary levels or record-keeping, do not just cause visa refusals. They can trigger compliance action, licence downgrades or enforcement visits.

For employers, the practical message is clear: build CoS management into your HR and compliance systems, not as a one-off process but as part of ongoing licence governance. That means ensuring multiple checks before assignment, keeping a full audit trail of documents, and monitoring usage against allocations. Treat each CoS as a compliance event, and you reduce the risk of problems that disrupt recruitment and threaten your sponsor licence. Getting it right the first time avoids wasted costs, lost candidates and unnecessary scrutiny from the Home Office.

Section G: Need Assistance?

DavidsonMorris’ specialist immigration lawyers are on hand to advise on all aspects of sponsor licence management, including allocations of Certificates of Sponsorship. If you have a query about a request for CoS, or any aspect of the sponsorship rules, contact us.

Section H: Defined & Undefined CoS FAQs

What is the difference between a Defined and an Undefined Certificate of Sponsorship?

A Defined Certificate of Sponsorship is used for Skilled Worker visa applicants applying from outside the UK. An Undefined Certificate of Sponsorship is used for applicants already in the UK, such as those switching visa categories or extending their stay, and for all other sponsored visa routes whether the application is made in-country or overseas.

Can I assign a Defined CoS immediately after requesting it?

No. You must first request the Defined CoS through the Sponsor Management System (SMS). The Home Office must approve the request before you can assign it to the worker. Decisions are usually made within one working day but can take longer if further checks are needed.

Do I need to request Undefined CoS each time I need one?

No. Employers are normally given an annual allocation of Undefined CoS. If your allocation is not sufficient, you must request an increase through the SMS. Requests can take several weeks to process, although a priority service is available for a fee and usually provides a decision within 5 working days.

How long is a Certificate of Sponsorship valid for?

A CoS is valid for three months from the date it is assigned. The visa application must be submitted within this period and no earlier than three months before the job start date. Once expired, a CoS cannot be reused.

What happens if I make a mistake on the CoS?

Mistakes can lead to the visa being refused or delayed. For Defined CoS, if key details are wrong, the certificate will usually need to be withdrawn and a new request made. For Undefined CoS, corrections are limited once assigned, so details must be checked carefully before submission.

Do I need to keep records after assigning a CoS?

Yes. Sponsors must keep detailed and accurate records for each sponsored worker, including the job description, contract, salary details and recruitment evidence. These must be available to the Home Office on request or during a compliance visit.

Is there a fee for assigning a CoS?

Yes. A CoS assignment fee is payable each time. For Worker routes (including Skilled Worker and Senior or Specialist Worker) the fee is £525. For Temporary Worker routes it is £55. International Sportsperson assignments cost £525 for over 12 months or £55 for 12 months or less. In addition, the Immigration Skills Charge is payable for most Skilled Worker and Senior or Specialist Worker assignments unless an exemption applies.

Can a Certificate of Sponsorship be reused?

No. A CoS is linked to a specific worker and job. If the worker does not use it, or the certificate expires, it must be cancelled and a new one assigned if the role remains available.

Will assigning a CoS trigger a Home Office compliance visit?

Not automatically. However, inaccurate or suspicious CoS assignments can increase the likelihood of a compliance visit or audit, especially in high-risk sectors such as health and social care. Every CoS should be treated as a compliance event.

Can I assign a CoS before the job start date is confirmed?

You can assign a CoS in advance, but the start date must be realistic and accurate. The visa will be tied to this date, and inconsistencies may cause problems during the application or later compliance checks.

Section I: Glossary

Section J: Additional Resources and Links