Certificate of Sponsorship Explained

There are two types of Certificate of Sponsorship:

• Defined CoS — Used when the worker is applying from outside the UK (entry clearance). Defined CoS must be allocated from a pool — there is a monthly allocation process for some occupation codes. The sponsor requests a defined CoS from UKVI, which is checked before it is issued.
• Undefined CoS — Used when the worker is already in the UK and is applying to extend, switch, or vary their leave in-country. Undefined CoS are assigned directly by the sponsor without prior UKVI approval, subject to the annual allocation limit.

Both types contain the same core information: the worker's personal details, the job title and SOC code, the salary, the start date, and the sponsor's details. Both are valid for three months from the date of assignment (defined CoS) or expiry (undefined CoS) — the visa application must be submitted within this period.

The Certificate of Sponsorship contains the following information that is critical to the visa application:

• The occupation code (SOC code) — This determines the going rate salary threshold and whether the role qualifies for the Skilled Worker route;
• The job title and description — Must accurately reflect the actual duties of the role;
• The gross salary — Must meet both the general Skilled Worker salary threshold and the specific going rate for the occupation code;
• The start date and end date — The visa will be issued to cover this period;
• The sponsor's licence number and name.

Any errors on the CoS must be corrected before the visa application is submitted. Once the visa application has been submitted, the CoS details cannot easily be changed. If the salary or role on the CoS does not match the actual job, this can be grounds for refusal.

A sponsor can withdraw a Certificate of Sponsorship before the visa is granted — for example, if a job offer is rescinded. If the CoS is withdrawn before the visa application is decided, the application will be refused (as the requirement to hold a valid CoS will no longer be met).

If the CoS is withdrawn after the visa is granted — which can happen if the employment relationship ends — the worker's visa may be curtailed (see the curtailment of leave guide). This gives the worker 60 days to find a new sponsor and apply for a new visa.

Workers should keep a record of their CoS reference number and the details on the CoS, as these will be needed when applying for visa extensions in future. The CoS reference is entered into the visa extension application form.

The Certificate of Sponsorship must accurately reflect the actual terms of employment at the point of assignment. The most frequent source of problems is a discrepancy between the information on the CoS and the actual job — whether due to an error in the original assignment or a subsequent change in the role. UKVI cross-references CoS details against the visa application form and may also verify information during compliance visits, so accuracy is essential both for the visa grant and for ongoing compliance.

The occupation (SOC) code is one of the most consequential entries on a CoS. The code determines which going rate applies and whether the role qualifies at the required skill level. Selecting the wrong code — even inadvertently — can result in a refusal if the correct code has a higher going rate that the proposed salary does not meet, or if the correct code is not at RQF level 3 or above (as required for the Skilled Worker route). Before assigning a CoS, employers should consult the Home Office's published Appendix Skilled Occupations to identify the correct SOC code for the actual duties of the role (not the job title), and verify that the proposed salary meets the applicable going rate for that code.

The start date is another common source of error. The start date on the CoS should be the date the worker will actually begin work, or as close to it as can be anticipated. If the start date passes before the visa is granted (for example, because processing takes longer than expected), the worker must not start work early. The CoS can be reissued with a revised start date, but this requires the existing CoS to be withdrawn and a new one assigned, which affects the three-month validity window for the visa application. Forward planning and realistic start dates reduce the risk of needing to reissue a CoS.

Workers should always obtain a copy of their CoS details — either from the employer or by asking for a screen print of the CoS record — before submitting the visa application. The visa application form requires entry of the CoS reference number and will pre-populate some fields from the CoS record. If there are any discrepancies between what the worker expected (based on their job offer) and what the CoS shows, these must be resolved with the employer before submission rather than after a refusal.

A Certificate of Sponsorship is only valid while the sponsoring employer holds a current, valid sponsor licence. If a sponsor licence is revoked or suspended, any CoS that has been assigned but on which a visa decision has not yet been made will cease to be a valid CoS — meaning the visa application will be refused. Workers in this position face a difficult situation: their application fails through no fault of their own, and they may not have had any prior knowledge that their sponsor was under investigation.

Workers who have submitted a visa application using a CoS from a sponsor whose licence is then revoked during the decision period should take urgent legal advice. In some circumstances it may be possible to withdraw the application (to avoid a formal refusal being recorded), find a new employer with a valid sponsor licence, obtain a new CoS from the new employer, and submit a fresh application — provided the applicant still meets the relevant requirements and has valid leave in which to make the application. If the applicant was applying from outside the UK, the application will be refused outright and a new entry clearance application from a different sponsor will be required.

To reduce the risk of this occurring, workers can check whether their prospective employer holds a valid sponsor licence using the public register of licensed sponsors, published on GOV.UK and searchable by name and location. This check takes only a few minutes and is advisable before accepting a job offer that will require immigration sponsorship. If a sponsor is on an A-rating on the register, their licence is currently valid. A B-rating means the sponsor cannot assign new CoS until compliance issues are resolved. Absence from the register means the employer does not hold a licence and cannot legally sponsor you.