What is CoS Activity and Why Does It Matter for Visa Sponsorship?

A Certificate of Sponsorship (CoS) is a digital record created by a licensed employer in the Home Office's Sponsorship Management System whenever they want to hire an international worker on a Skilled Worker, Global Business Mobility, or other sponsored visa route. Each CoS is assigned a unique reference number that the worker uses when applying for their visa.

For a visa to be granted, a valid CoS must exist. This makes CoS issuance the definitive measure of actual sponsorship activity — it is not self-reported by employers, it is recorded directly in the Home Office's own system every time a sponsorship takes place.

The number of CoS an employer has issued is therefore a direct measure of how often they have actually sponsored international workers — not how willing they are to in theory, but how often they have done it in practice.

The Home Office releases quarterly transparency data on sponsor licence holders, including information on CoS issuance. VisaAtlas processes this data and aggregates it at the employer level, showing how many CoS each licensed sponsor has issued over different time periods. This is the same underlying data source used by researchers, journalists, and immigration professionals to analyse sponsorship trends.

The data is published with a lag — typically one to two quarters behind the current date. This means very recent changes in an employer's hiring activity (for example, a company that started a major international recruitment drive two months ago) may not yet be reflected fully in the numbers. However, the historical data provides a robust picture of an employer's established sponsorship patterns.

VisaAtlas enriches this raw transparency data with additional signals — such as live job postings, company information, and hiring pattern analysis — to produce a more complete picture of each sponsor's current activity level. The CoS data is the most objective input, but it works best in combination with other signals.

A high CoS volume tells you that an employer is experienced at sponsoring international workers and has done so recently and repeatedly. This has several practical implications: their HR team knows the process well, they are unlikely to be surprised or deterred by the administrative burden of sponsorship, they likely have existing relationships with immigration solicitors or advisory firms, and they are less likely to make costly errors on the Certificate of Sponsorship that could delay your application.

High CoS activity does not guarantee that a current vacancy exists for your specific role, or that your particular occupation code and salary would be eligible. A company could issue 200 CoS per year — all for nurses — but have no vacancies for engineers. CoS activity is a proxy for sponsorship willingness and infrastructure, not a guarantee of a matching vacancy.

Similarly, a company with low or zero recent CoS activity is not necessarily a bad employer or one that would refuse to sponsor. They may simply have not needed to recruit internationally recently. Some excellent employers have low CoS volume because they primarily recruit domestically. However, they represent more uncertainty: you do not know how familiar their HR team is with the process, and the process may take longer if they need to research it.

An employer that issued 500 CoS three years ago but zero in the past 12 months is a different prospect from one that issued 50 last year. The older data tells you the company has used sponsorship at scale, which is useful context — but it does not tell you whether they are currently hiring internationally or whether their sponsorship infrastructure is still active.

Recency of CoS issuance is one of the most important factors to consider. An employer with recent activity signals that their sponsor licence is being actively managed, that their HR team is current on the rules, and that international recruitment is part of their current operations — not just a historical phase.

On VisaAtlas, you can filter and sort sponsors by recent CoS activity, prioritising employers with issuance in the past 6 or 12 months. This is particularly useful in sectors where sponsorship patterns fluctuate — for example, care providers that ramped up international recruitment significantly in 2022–23 may have since scaled back, and a company showing high historical volume but no recent activity may not currently be running international recruitment campaigns.

The VisaAtlas sponsor search allows you to filter sponsors by CoS activity level and sort the results by recent issuance. A practical approach is to start with a broad search of your target sector and city, then apply a CoS activity filter to show only employers with meaningful recent issuance — for example, at least 10 CoS in the past 12 months.

This approach typically reduces a large list of hundreds or thousands of potential sponsors down to a much more focused shortlist of employers genuinely active in international hiring. You can then review each company's profile in more detail — their sponsor rating, industries, locations, and any live job postings on the VisaAtlas jobs board — to identify the strongest targets for direct applications.

CoS activity filtering is one of the most time-efficient things you can do early in your sponsorship job search. A targeted list of 20 highly active sponsors in your sector will almost always yield better results than a broad list of 500 sponsors with mixed or low activity levels.