Defined CoS vs Undefined CoS

In This Article

• What are the two types of CoS?
• Defined CoS: entry clearance from abroad
• Undefined CoS: in-country applications and other visas
• Side-by-side comparison
• The allocation process
• Which type do you need?
• Common mistakes to avoid
• Frequently asked questions
• Related terms

What are the Two Types of CoS?

The Home Office distinguishes between two categories of Certificate of Sponsorship based on the visa route and, for Skilled Workers, on whether the applicant is inside or outside the UK:

• Defined CoS: For Skilled Workers applying from outside the UK (entry clearance applications)
• Undefined CoS: For Skilled Workers applying from inside the UK (switching visa categories or extending an existing visa), and for applicants on all other visas

This distinction matters because the two types are allocated and approved through completely different processes.

Our page of Skilled Worker visa statistics shows how many Skilled Worker visas are granted each quarter to people applying from outside the UK, who need a defined CoS, and to people switching or extending inside it, who need an undefined one.

Defined CoS

A Defined CoS is required when a Skilled Worker is applying for a UK visa from outside the UK. It is called "defined" because the employer must apply to the Home Office for each individual CoS before it can be assigned to the worker.

Key characteristics:

• Each Defined CoS must be separately requested and approved by the Home Office
• Applications are assessed. UKVI checks that the role and salary meet the rules before granting the CoS
• Once approved, the employer assigns it to the named worker
• The worker then uses the CoS reference number in their visa application from abroad

Processing time: GOV.UK says defined certificate applications are usually approved within one working day. It can take longer if UKVI need to carry out further checks.

Undefined CoS

An Undefined CoS is used when a Skilled Worker is applying from inside the UK and is either:

• Switching from one visa category to another (e.g., student to Skilled Worker)
• Extending their existing Skilled Worker visa (often with a new employer)

GOV.UK also says undefined certificates are used for applicants on all other visas.

It is called "undefined" because the employer does not need prior Home Office approval for each CoS. Instead, sponsors receive an annual allocation of Undefined CoS from the Home Office (based on their historical usage), and they draw from this pool as needed via the Sponsorship Management System.

Key characteristics:

• Drawn from the employer's pre-allocated annual supply — no per-CoS approval needed
• Faster to assign once the allocation is in place
• For Skilled Workers, used only when the worker is applying from inside the UK
• The worker then includes the CoS reference in their in-country visa application (permission to stay)

Side-by-Side Comparison

The Allocation Process

Undefined CoS allocation: A new sponsor asks for a number of Undefined CoS for its first year when it applies for its licence, and must justify the request. UKVI decides the allocation, and it can be lower than the request. Each year, an eligible sponsor's allocation is renewed automatically at the number of CoS it assigned the year before. Sponsors can request additional CoS via the SMS if they run out. Approval of additional allocation is not guaranteed. GOV.UK says a decision usually takes up to 12 weeks, or 5 working days if the sponsor pays for the priority service.

Defined CoS allocation: There is no pre-allocated supply of Defined CoS. Each one must be applied for individually through the SMS, and GOV.UK says it is usually approved within one working day.

Which Type Do You Need?

Note: Applicants who entered the UK on a Standard Visitor visa cannot switch in-country — they must return home and apply with a Defined CoS.

Common Mistakes to Avoid

• Assigning an Undefined CoS where a Defined one is required. For a Skilled Worker applying from outside the UK, the visa application can be refused, and GOV.UK says UKVI will normally revoke the sponsor's licence.
• Applying late for a Defined CoS. GOV.UK says approval is usually within one working day, but further checks can take longer, so leave some time.
• Running out of Undefined CoS allocation without topping up. Request additional allocation proactively; don't wait until you've run out.
• Confusing entry clearance with permission to stay. The terminology on the SMS can be confusing — double-check which application type the worker will be making.

Frequently Asked Questions

Can a worker use an Undefined CoS if they are temporarily in the UK on a business visa?

No. Workers who entered the UK on a Standard Visitor visa cannot switch in-country. They must leave the UK and apply with a Defined CoS for entry clearance.

How many Undefined CoS does a new sponsor get?

It depends on the sponsor. When it applies for a licence, a new sponsor says how many it expects to need in its first year and must justify the number. UKVI decides the allocation, which can be lower than the request. During the year the sponsor can ask for more through the SMS and must give reasons.

Can the employer reassign a CoS to a different worker?

No. Once a CoS is assigned to a named worker, it cannot be reassigned. If the original worker does not proceed, the CoS must be withdrawn and a new one issued for the replacement candidate.

Is there a different fee for Defined vs Undefined CoS?

No. GOV.UK sets the certificate fee by the type of sponsor licence, with no separate rate for defined or undefined certificates: it is £525 for a Skilled Worker. The Immigration Skills Charge, where it applies, is the same too. The difference is in the process: an employer applies for each defined certificate, which is usually approved within one working day, and draws undefined ones from its annual allocation.

Related Terms

• Certificate of Sponsorship
• CoS Expiry & Validity
• Sponsor Licence
• Changing Visa Sponsors

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