Certificate of Sponsorship (CoS)

A Certificate of Sponsorship, usually shortened to CoS, is the employer's confirmation to the Home Office that it is offering you a specific job. GOV.UK describes it as an electronic record, not a physical document, with a unique reference number you need for your visa application. The employer creates it in the Home Office sponsorship management system (SMS).

The certificate records the details the Home Office checks against your application, including your job title, occupation code, salary and start date, and whether the employer will certify your maintenance so you do not have to show personal savings. Only a licensed sponsor can assign one.

Anyone applying for a sponsored work visa in the UK needs a CoS. For health professionals this mainly means the Health and Care Worker visa and the Skilled Worker visa. You need a new certificate when you first apply and when you change employer or move to a job with a different occupation code.

GOV.UK describes two types:

• Defined certificates are for Skilled Worker applicants applying from outside the UK. The employer requests each one through the SMS, and GOV.UK says requests are usually approved within one working day.
• Undefined certificates are for Skilled Workers applying from inside the UK and for other visa routes. The employer estimates how many it needs when it applies for its licence.

1. Accept a job offer from a UK employer that holds a sponsor licence.
2. The employer assigns the certificate and sends you the reference number.
3. Check the job title, occupation code, salary, hours and start date before you apply. Errors can lead to refusal.
4. Apply for your visa using the reference number within 3 months of receiving it, and no more than 3 months before the start date on the certificate.

For nurses recruited before passing the NMC test of competence, or anyone starting in a lower band, the certificate will carry the code and salary of that first role, not the role you move into later.

GOV.UK says the employer pays £525 for each certificate on a Worker licence. Sponsors of Skilled Worker and Senior or Specialist Worker visas may also have to pay the immigration skills charge, which GOV.UK sets at £480 for the first 12 months for small or charitable sponsors and £1,320 for medium or large sponsors, with further amounts for each extra 6 months.

The employer must pay these costs. GOV.UK warns that a sponsor's licence may be revoked if it asks the worker to pay sponsorship costs. Your own visa fee is separate and is paid by you unless your employer agrees otherwise.

• Letting the certificate expire. A certificate that is not used within 3 months cannot support a visa application.
• Mismatched details between the certificate, your contract and your documents.
• A certificate is not a visa. GOV.UK notes that sponsorship does not guarantee a visa will be granted.
• Being asked to repay the fees. The certificate and skills charge are the employer's costs under the sponsorship rules.

See our Health and Care Worker visa guide for how the certificate fits the full application.