Certificate of Sponsorship (CoS) Explained

What is a Certificate of Sponsorship?

A Certificate of Sponsorship (CoS) is not a paper document. It is an electronic record created by a licensed UK employer inside the Home Office's Sponsorship Management System (SMS). When your employer assigns you a CoS, you receive a unique CoS reference number — a string of letters and numbers you enter when you apply for your Skilled Worker visa on GOV.UK.

Without a valid CoS from a licensed sponsor, you cannot apply for a Skilled Worker visa (or most related work routes). This is why verifying that an employer is genuinely licensed is so important before you accept a job offer.

Two types of CoS: Defined and Undefined

There are two types of Certificate of Sponsorship, and they work differently:

• Defined CoS — normally requested for a Skilled Worker applying for entry clearance from outside the UK. The sponsor requests it through the Sponsor Management System and must receive allocation approval before assignment.
• Undefined CoS — normally assigned from the sponsor's annual allocation for a Skilled Worker applying for permission to stay from inside the UK and for other eligible routes where the guidance specifies an Undefined CoS.

What a CoS confirms

When your employer assigns you a CoS, the electronic record typically includes:

• Your full name and date of birth (must match your passport exactly)
• Your job title and the Standard Occupational Classification (SOC) code for your role
• Your confirmed annual salary and start date
• Your employer's sponsor licence number and details
• Whether the role is eligible under the Skilled Worker route
• The visa route being sponsored (e.g. Skilled Worker, Health and Care Worker)

CoS validity — you have 3 months to use it

Once a CoS is assigned to you, you must use the reference number to submit your visa application within 3 months. After that, the CoS expires and your employer must request a new one. Make sure you apply promptly once you have your CoS reference number.

Who can issue a CoS?

Only employers on the Home Office Register of Licensed Sponsors can assign a CoS. If a company is not on this register, they cannot legally sponsor your visa — regardless of what they claim. Use FindMySponsor or our sponsor licence check guide to verify any employer before you accept an offer.

The Immigration Skills Charge — paid by your employer

When your employer assigns a CoS, it may also have to pay the Immigration Skills Charge (ISC). The current charge is £480 for the first 12 months for a small or charitable sponsor or £1,320 for a medium or large sponsor, followed by £240 or £660 for each additional six months. Occupation and other exemptions apply. The sponsor must pay the ISC and the £525 Worker CoS assignment fee itself; asking the worker to reimburse these costs can put its licence at risk.

What happens after you get your visa

The CoS is only used for the visa application stage. Once your visa is granted, you simply start work with your employer on the agreed start date. Your employer must continue to comply with their sponsor duties (tracking attendance, reporting changes) throughout your employment — the CoS becomes an archived record in the SMS.

Next steps

• How to get visa sponsorship in the UK — full step-by-step
• Skilled Worker eligibility requirements
• How to check a UK sponsor licence
• How to spot fake sponsorship scams