In This Guide
The Certificate of Sponsorship is the foundation document for any Health and Care Worker visa application. Without a valid CoS, you cannot apply for or renew your visa. Yet many care workers are unsure about what a CoS actually is, what it should contain, and what to do if something is wrong with it.
This guide explains everything you need to know about the CoS in plain English, helping you understand your rights and responsibilities.
What Is a Certificate of Sponsorship?
A Certificate of Sponsorship (CoS) is an electronic record — not a physical document — that is created by your employer through the Home Office's Sponsorship Management System (SMS). Think of it as a digital reference number that links you to your sponsoring employer.
Each CoS has a unique reference number that you include in your visa application. The Home Office uses this number to verify that a licensed employer is willing to sponsor you for a specific role at a specific salary.
Key fact
A CoS is NOT a guarantee that your visa will be approved. It is simply confirmation that a licensed employer wants to hire you. The Home Office still assesses your overall eligibility including English language, salary, and maintenance requirements.
CoS vs. Sponsor Licence
Do not confuse the CoS with a Sponsor Licence. The Sponsor Licence is the permission the Home Office grants to your employer to hire overseas workers. The CoS is the individual record they create for each worker they want to sponsor. An employer must have a valid Sponsor Licence before they can assign a CoS to any worker.
Types of Certificate of Sponsorship
There are two types of CoS, and which one you need depends on where you are when you apply:
Defined CoS
For workers applying from outside the UK. The employer must request a defined CoS from the Home Office for each individual worker. There is an annual allocation process, though Health and Care Worker route CoS are generally not capped.
- Assigned to a named individual
- Used for entry clearance applications
- Valid for 3 months
Undefined CoS
For workers applying from inside the UK — for example, when switching sponsors or extending your visa. Employers have an annual allocation of undefined CoS certificates that they can assign as needed.
- Drawn from employer's annual allocation
- Used for in-country applications
- Valid for 3 months
What Information Does a CoS Contain?
A CoS contains detailed information about you, your role, and your employer. Here is what each section includes:
| Section | Details Included |
|---|---|
| Personal details | Full name, date of birth, nationality, passport number |
| Job details | Job title, SOC code, description of duties, hours per week |
| Salary | Annual gross salary, any allowances, overtime arrangements |
| Work location | Primary work address (and any secondary locations) |
| Dates | Start date, end date (if fixed-term), CoS assignment date |
| Sponsor details | Employer name, sponsor licence number, contact person |
| Maintenance | Whether the employer certifies your maintenance (financial support) |
How a CoS Is Assigned
The process of assigning a CoS is handled entirely by your employer. Here is how it works step by step:
Employer offers you the job
Your employer goes through the normal recruitment process including advertising the role, interviewing, and making a formal offer.
Employer completes right-to-work checks
They verify your identity, qualifications, and ensure the role is genuine and meets the minimum salary for the SOC code.
Employer logs into SMS and creates the CoS
The employer's authorising officer or Level 1 user logs into the Home Office Sponsorship Management System and enters all required details to create the CoS record.
Employer assigns the CoS to you
Once completed and reviewed, the CoS is assigned and a unique reference number is generated. The employer pays the £239 fee at this point.
You receive the CoS reference number
Your employer shares the CoS reference number with you so you can include it in your visa application. This is usually a string of letters and numbers.
What to Check on Your CoS
Critical: Errors on your CoS can lead to your visa application being refused. Always ask your employer for a summary of the CoS details before they assign it, and check everything carefully.
Your name is spelled correctly
Must match your passport exactly, including middle names
Date of birth is correct
Must match your passport
Job title and SOC code are correct
Must be an eligible occupation (e.g., SOC 6145 for Care Workers)
Salary meets minimum requirements
Must be at least the going rate for your SOC code. See our salary requirements guide
Working hours are accurate
Full-time hours and any overtime arrangements should match your contract
Work location is correct
The address where you will primarily work (important for domiciliary care workers)
Start date is realistic
Allow enough time for your visa to be processed before the start date
Maintenance certification
Check whether your employer is certifying maintenance — if not, you need £1,270 in savings
Common CoS Problems and Solutions
Problem: Your employer is taking too long to assign the CoS
Some employers delay assigning a CoS. While there can be legitimate administrative reasons, excessive delays (more than 2-3 weeks after your right-to-work documents have been submitted) may be a red flag.
Solution: Politely follow up in writing. If delays persist, consider whether this employer is right for you. A good employer processes CoS promptly.
Problem: Errors on the CoS
If you spot errors after the CoS has been assigned, do not submit your visa application with incorrect details.
Solution: Ask your employer to withdraw the CoS and assign a corrected one. They can do this through the SMS system. It costs them another £239 but this is the employer's responsibility.
Problem: Employer wants you to pay for the CoS
The CoS fee (£239) is the employer's cost. It is not permitted for employers to deduct this from your wages or ask you to reimburse it.
Solution: Refuse and report this to the Home Office. An employer who tries to charge you for the CoS is breaching their sponsor duties. See our exploitation rights guide.
Problem: CoS has expired before you applied
A CoS is valid for 3 months. If you miss the window, it expires and cannot be used.
Solution: Contact your employer immediately. They will need to assign a new CoS. Plan your application timeline carefully to avoid this.
Employer Sponsorship Duties
When an employer holds a sponsor licence and assigns a CoS, they take on significant legal obligations to the Home Office. Understanding these helps you know what to expect from your sponsor:
- Record keeping: Employer must keep copies of your passport, right-to-work documents, and contact details
- Reporting duties: Must report to the Home Office if you fail to start work, are absent for more than 10 working days without authorisation, or if your employment ends
- Pay and conditions: Must pay at least the salary stated on the CoS and not make unauthorised deductions
- Genuine vacancy: The job must be a real role with genuine duties, not created solely for immigration purposes
- Cooperation with UKVI: Must allow Home Office compliance visits and provide documents when requested
If your employer breaches these duties, their sponsor licence can be downgraded to B-rated or revoked entirely. If their licence is revoked, you will receive a 60-day curtailment letter. Read our switch sponsor guide to know what to do.
Frequently Asked Questions
What is a Certificate of Sponsorship (CoS)?
A Certificate of Sponsorship is an electronic document issued by a UK employer with a valid sponsor licence. It contains details about the job role, salary, and working conditions. It is not a physical certificate but a reference number assigned through the Home Office's Sponsorship Management System. You need a CoS reference number to apply for or extend your Health and Care Worker visa.
How long is a CoS valid?
A CoS is valid for 3 months from the date it is assigned. You must use it to submit your visa application within this period. If you do not use it in time, your employer will need to assign a new one.
Does my employer pay for the CoS?
Yes, the employer is responsible for paying the CoS fee, which is currently £239. This cost cannot be passed to the worker. If your employer asks you to pay for the CoS, this is not permitted and you should report it.
Can I get a CoS from more than one employer?
You can only have one active CoS at a time for the same visa route. However, if you are switching employers, your new employer can assign you a CoS while your current one is still active.
What information does a CoS contain?
A CoS contains your personal details, job details (title, SOC code, duties), salary information, start date, work location, and the sponsor's details. It also confirms whether the employer will certify your maintenance.
What should I check on my CoS?
Verify your name and personal details match your passport, the job title and SOC code are correct, the salary meets the minimum threshold, the work address is accurate, and the start date is realistic. Any errors can delay or cause refusal of your visa application.