Certificates of Sponsorship (Defined vs Undefined CoS)
Understanding the electronic work permits issued through the Sponsor Management System (SMS).
Checked against official Immigration Rules & GOV.UK guidance on 2026-10-30
A Certificate of Sponsorship (CoS) is not a physical paper document; it is a digital reference number generated on the Home Office Sponsor Management System (SMS) that an employer assigns to an international worker so they can apply for their visa.
Defined vs Undefined CoS
- Defined CoS: Required for Skilled Workers applying from outside the UK. Employers must submit an individual application via the SMS for each candidate, specifying the job title, SOC code, and salary. Approval takes approximately 24 to 72 hours.
- Undefined CoS: Used for workers applying from inside the UK (such as switching from a Student or Graduate visa), or for extensions and Global Business Mobility routes. Employers request an annual batch allocation each April.
Key Requirements & Highlights
- CoS assignment fee: £239 per certificate (exempt for select temporary routes).
- Immigration Skills Charge (ISC) payable upon assigning CoS (£364/year small, £1,000/year large).
- Defined CoS must be approved by the Home Office prior to assignment.
- CoS reference number is valid for 3 months from assignment.
Step-by-Step Application Timeline
- Select TypeDetermine whether candidate requires Defined CoS (overseas) or Undefined CoS (in-country).
- SMS AssignmentComplete candidate passport details, work dates, SOC code, salary, and pay ISC fee.
- Visa ApplicationCandidate uses unique CoS number to submit visa on GOV.UK within 3 months.
Frequently Asked Questions
What is the Immigration Skills Charge (ISC)?
The ISC is a statutory charge payable by the employer upon assigning a CoS to a Skilled Worker. Small sponsors pay £364 for the first 12 months plus £182 for each additional 6 months. Medium/large sponsors pay £1,000 per year.
Need Guidance on Your Application?
Priyanshu Decodes provides clear route explanations, document planning, and consultation calls. For regulated legal advice or formal Home Office representation, always consult an IAA-registered adviser or an immigration solicitor.