A Certificate of Sponsorship (CoS) is an electronic reference assigned by a licensed UK employer (sponsor) to a foreign worker they wish to hire. It’s not a paper document, but a unique 8-digit number in the Home Office’s system. Each CoS contains details of the worker’s role (job title, salary, start date, etc.) and the sponsoring company. The CoS number must be quoted in the worker’s UK visa application, as it provides UKVI with the information needed to approve the visa. For example, the Skilled Worker visa specifically requires “a certificate of sponsorship (CoS) from your employer with information about the role you’ve been offered”. Once issued, the worker has 3 months to apply for the visa (and cannot apply more than 3 months before the CoS start date). In short, a CoS is essential for UK work visas: without it, the visa application will be refused.
UK Visa Categories That Require a CoS
Most of the UK’s points-based work visas require a sponsor licence and a CoS. Key categories include:
- Skilled Worker visa (formerly Tier 2 General) – For long-term skilled jobs. The employer must have a Worker sponsor licence and issue a CoS. This includes the Health and Care Worker visa. (Requirement: eligible job and minimum salary on the occupation list.).
- Global Business Mobility (GBM) visas – For intra-company and international transfers. Employers with a GBM-approved licence can sponsor: Senior/Specialist Workers (high-level transfer), Graduate Trainees, Service Suppliers, UK Expansion Workers, and Secondment Workers. Each of these GBM routes requires a CoS issued under the Worker licence.
- Temporary Worker visas – Short-term or specified routes. Sponsors with a Temporary Worker licence can issue CoS for categories such as:
- Scale-up Workers (high-growth companies),Creative Worker (entertainers, artists),Charity Worker (volunteers),Religious Worker (short-term religious roles),Government Authorised Exchange (training/research exchanges),International Agreement (workers covered by treaties),Graduate Trainee (GBM),Service Supplier (GBM),UK Expansion Worker (GBM),Secondment Worker (GBM),Seasonal Worker (horticulture/poultry up to 6 months).
Defined vs. Undefined Certificates of Sponsorship
Within the Skilled Worker route, there are two types of CoS:
- Defined CoS: Used when hiring from outside the UK. The sponsor must first apply for a Defined CoS allocation in the SMS and get approval from UKVI. Once approved, the CoS is issued and can be assigned to that specific job offer.
- Undefined CoS: Used for hires inside the UK (switching visas) or roles on other Worker/Temporary routes. These come from the sponsor’s annual CoS allocation (an estimated quota requested when applying for the licence).
It’s crucial not to mix them up: a Defined CoS must only be used for the particular overseas hire it was approved for, and cannot be given to another role or worker; an Undefined CoS (from your quota) cannot be used for an overseas hire who requires a Defined CoS. Assigning the wrong type of CoS or falsifying information can lead to licence revocation.
How Employers (Sponsors) Assign a CoS
Only licensed UK employers can issue CoS. To become a sponsor, a company must apply online for a sponsor licence (Worker and/or Temporary Worker) and meet UKVI’s requirements. Licence fees depend on business size: for example, a large company pays £1,579 for a Worker licence. Once approved, the sponsor uses the Home Office’s Sponsorship Management System (SMS) to issue CoS.
Steps to assign a CoS:
- Obtain licence: Ensure you have the correct licence type (Worker and/or Temporary Worker). Meet all eligibility checks (no disqualifying convictions, genuine business, etc.).
- Request Defined CoS (if needed): For overseas Skilled Worker hires, apply for a Defined CoS via SMS and wait for approval (usually ~1 working day).
- Assign in SMS: Once the CoS is available (Defined approved or using your Undefined allocation), fill in the worker’s details in SMS and assign the CoS. You must be A-rated to assign (except limited cases). The CoS record will include the worker’s name, passport info, job title, occupation code, salary, start/end dates, and work location.
- Pay fees: You must pay the CoS issuance fee at assignment. Currently this is £525 for a Skilled Worker (Worker licence) CoS and £55 for most Temporary Worker CoS. Note: if assigning a Skilled Worker or Senior/Specialist Worker CoS, you may also need to pay the Immigration Skills Charge.
After assigning, inform the worker of the CoS number. They must use that number on their visa application within 3 months. Keep all records of the CoS and related employment, as you’ll need them for compliance checks.
Sponsor Responsibilities and Compliance
Being a sponsor carries important legal duties. According to UKVI guidance, sponsor duties include:
- Reporting: Notify UKVI of any significant changes (e.g. job ending early, absences of 10+ days, salary changes, worker contact details) within required timeframes.
- Record-keeping: Maintain up-to-date records for each sponsored worker (passport copies, contact info, job records, etc.).
- Adherence to laws: Ensure the sponsored role and worker continue to meet immigration rules and UK employment law. Do not conduct activities “not conducive to the public good”.
Failure to meet these duties can lead to severe sanctions: UKVI may downgrade your licence, reduce or withdraw your CoS allocation, or even revoke your licence entirely.
Importantly, recent rule changes prohibit sponsors from recovering certain costs from workers. From end-2024 onwards, you may not charge the employee for the CoS fee or your licence fee. (Exceptions allow recouping visa application costs under strict conditions, but not the sponsor-specific fees.) Violating this will risk licence suspension.
Guidance for Applicants (Workers)
If you are the sponsored worker, a few points on using the CoS:
- Check your CoS: Ensure your employer is on the official Register of Sponsors and that the CoS is for the correct job and salary. Verify your name and details on the CoS.
- Visa application: Use the CoS reference number when you apply for your visa or visa extension. Apply online within 3 months of the CoS being assigned (but no more than 3 months before your start date). Provide all required documents (proof of CoS, salary, and other eligibility evidence) as directed by the visa guidance.
- Timing: Plan your visa application so that you arrive in the UK on or shortly before the CoS start date. You cannot enter more than 14 days early.
- Changes after assignment: If your job details (role, salary, or employer) change before you start, do not proceed without updating. The sponsor may need to withdraw the old CoS and issue a new one. Using an incorrect CoS will cause refusal.
- If sponsor loses licence: If your employer’s licence is revoked while you’re in the UK, your CoS is cancelled and your visa will normally be curtailed to 60 days. You must either find a new sponsor (and get a new visa) or leave the UK. If you are outside the UK when the licence is lost, any pending visa application will be refused.
Always follow the advice of your employer’s immigration adviser and keep copies of all communications. Remember, the CoS itself does not guarantee a visa – you still must meet all other visa requirements.
2025 Updates and Key Changes
Several changes took effect in 2024–2025 that affect Certificates of Sponsorship and sponsorship:
- Fee increases: Sponsor licence and CoS fees have risen. As of April 2025, a large employer pays up to £1,579 for a Worker licence (Temporary licence is £574). The CoS fee for a Skilled Worker or similar route is now £525 (120% higher than before). (Temporary Worker CoS fees remain £55.)
- No cost passing: As noted above, sponsors cannot charge the CoS or licence fee to employees after late 2024. This is part of broader reforms to protect migrant workers.
- Salary thresholds: From 9 April 2025, the minimum salary for certain Skilled Worker visas has increased. New entrants (e.g. junior health care roles, PhD candidates, STEM PhDs) now need at least £25,000 per year (£12.82/hour). The general Skilled Worker minimum remains £38,700 (or the going rate for the occupation, whichever is higher).
- Scale-up route: For Scale-up Worker visas, sponsors have a unique rule: after 6 months in the UK, the employer’s sponsorship duties end. The worker can then continue or change jobs without a new CoS or new sponsor. This gives flexibility to fast-growing companies.
- Care sector rule: A new requirement (from April 2025) asks care employers to consider local UK-trained care workers from a Home Office pool before assigning new CoS for certain care roles. This is a niche change but worth noting for care sponsors.
These updates reflect the latest Immigration Rules as of 2025. (Further changes may come from the UK’s post-Brexit immigration White Paper proposals, but those are not law yet.) Always check GOV.UK or legal guidance for the most current regulations.
FAQs
Q: What exactly is a Certificate of Sponsorship (CoS)?
A CoS is a digital reference number issued by a UK employer (who holds a valid sponsor licence) to a foreign worker. It contains details of the job and employer and is required for work visas like the Skilled Worker. It is used to apply for the visa – think of it as the employer’s formal job offer recorded for UKVI.
Q: Which UK work visas need a CoS?
Most “Worker” visas in the points-based system do. This includes the Skilled Worker visa (including the Health & Care Worker variant), the Scale-up Worker visa, all Global Business Mobility routes (e.g. Senior/Specialist, Graduate Trainee, etc.) and Temporary Worker visas (Creative, Charity, Religious, Government Authorised Exchange, International Sportsperson, Seasonal Worker, etc.). Student, visitor, and family visas do not use a CoS – they have other documentation.
Q: What is the difference between a Defined and Undefined CoS?
For Skilled Workers: a Defined CoS is applied for and assigned to a new hire coming from outside the UK. The employer must request a Defined CoS through the SMS and await UKVI approval before giving it to the worker gov.uk. An Undefined CoS is drawn from the employer’s existing CoS allocation and is used when the worker is already in the UK (e.g. switching visas) or on any other sponsored route gov.uk. You must use the correct type, or UKVI can revoke your licence.
Q: How does an employer assign a CoS?
First, the employer needs a valid sponsor licence (Worker and/or Temporary Worker) gov.uk. In the Sponsorship Management System (SMS), the employer inputs the migrant’s details and the job specifics to assign the CoS. For overseas Skilled Workers, a Defined CoS must be requested first gov.uk; for others, an Undefined CoS is taken from your allocation. The employer then pays the CoS fee and (if applicable) the Immigration Skills Charge, and provides the CoS reference to the worker.
Q: What responsibilities do sponsors have after assigning a CoS?
Sponsors must comply with reporting and record-keeping duties. This means updating UKVI on significant changes (for example, if the worker leaves the job early, or is absent for 10+ days) and keeping accurate records (like copies of passports, contact info, etc.). They must also ensure the job and worker remain compliant with immigration rules and UK law assets.publishing.service.gov.uk. If a sponsor breaches these duties, UKVI can downgrade or revoke the licence and cancel CoS allocations. Also, sponsors cannot charge the worker for the CoS or licence fee as of late 2024.
Q: Can an employer charge me for the CoS or licence?
No. Under the current rules, sponsors may not require workers to pay any part of the CoS issuance fee or the sponsor licence fee gov.uk. Attempting to recover these costs from the employee is a breach of the rules and may lead to licence sanctions. (Sponsors may charge for actual immigration advice if the worker opts in, but that is separate.)
Q: How long is a CoS valid?
Once assigned, a CoS is valid for 3 months. The worker must apply for their visa within that period. If the CoS expires without use, a new one must be assigned. Also, the visa start date cannot be more than 3 months after assignment, and not earlier than the date on the CoS.
Q: What if my sponsor loses or loses their licence?
If your UK employer’s sponsor licence is revoked while you have a valid CoS, UKVI will cancel the CoS and curtail your visa to 60 days gov.uk. You must leave the UK or apply for a new visa with a different sponsor. If you haven’t yet started work (or are outside the UK), your visa application will be refused or cancelled immediately. To avoid surprises, check your employer’s status on the official Register of Sponsors before starting.
Q: Have the CoS rules changed in 2025?
Yes, there were several updates. The costs have risen: a Skilled Worker CoS now costs £525, and licence fees can be £1,579 for large companies. Importantly, as noted, employers can no longer pass these fees to workers. The minimum salary thresholds for Skilled Worker visas were also increased in April 2025 (for example, certain entry-level roles now require £25,000/year). New rules (from April 2025) also affect specific sectors (e.g. care worker recruitment). Always check the latest Home Office guidance, as the immigration landscape continues to evolve.
Q: Where can I find more information?
Official UK government guidance is the best source: see GOV.UK pages on sponsoring workers, certificates of sponsorship, and specific visa routes. Immigration advisers and reputable law firm guides (e.g. sponsorship guidance for employers) can also help explain the details.
This comprehensive overview should equip both sponsors and applicants with a clear understanding of the Certificate of Sponsorship – what it is, which visas need it, and the latest rules for 2025. Always ensure compliance with UKVI requirements and stay updated on any rule changes.
Sources: Authoritative UK government guidance and legal analysis (Home Office and law firms) were used to ensure accuracy gov.uk, gov.ukgov.uk, chambers.com, assets.publishing.service.gov.uk