A Certificate of Sponsorship is a digital record your licensed sponsor organisation assigns to a migrant worker: it proves you intend to sponsor them and sets out immediate duties, but it does not by itself guarantee a visa. Only sponsors holding a valid licence can assign one, and the worker must use the CoS reference in their application within three months of assignment.
TL;DR:
- A defined CoS is necessary for overseas entry clearance applications and requires validation through SMS before requesting it from A-rated sponsors.
- Incorrect details on a CoS, such as SOC code or salary, can lead to application refusals or compliance issues, so careful pre-approval checks are essential.
- The CoS must be used within three months of assigning, and both the assignment fee and the Immigration Skills Charge significantly add to sponsorship costs over time.
- Sponsors must maintain detailed records and promptly report any job, salary, or contact changes to avoid penalties or license suspension.
- Legal help from qualified immigration solicitors can ensure correct CoS requests, reduce compliance risks, and handle complex sponsorship issues efficiently.
Table of Contents
- What a Certificate of Sponsorship actually records
- Defined versus undefined CoS: which one do you need?
- Requesting, assigning and using a CoS: the practical workflow
- Fees and charges: CoS assignment and the Immigration Skills Charge
- Sponsor duties, record keeping and compliance risk
- Common mistakes and how to avoid them
- Timelines: how long each step takes and how long a CoS lasts
- When to get professional legal help with CoS matters
- An experienced view on getting CoS right the first time
- How MNS Solicitors supports employers through CoS and sponsorship
- Where to check official CoS guidance
- Sources
- FAQ
What a Certificate of Sponsorship actually records
A Certificate of Sponsorship is not a paper document you print and hand over. It is an electronic record held in the Sponsorship Management System (SMS), also known as SpUK, carrying a unique reference number the worker enters into their visa application. That reference links the worker’s case directly to your organisation as sponsor.
The CoS confirms the job title, the Standard Occupational Classification (SOC) code, the salary and start date, and it stands as your formal declaration that you will meet your sponsor duties for that individual. Assigning a CoS is a distinct step from the worker actually meeting the route’s eligibility requirements: you confirm the job exists and pays correctly, but the Home Office still assesses the worker’s own qualifications, English language ability and financial requirements separately.
For employers new to sponsorship, it helps to understand the moving parts before you request one:
- The CoS number is entered on the worker’s online visa application and checked against Home Office records.
- The employer’s declaration on the CoS becomes part of the compliance record the Home Office can later audit.
- A CoS ties to one worker and one role; it cannot be transferred to another person or repurposed for a different job.
- Incorrect details on the CoS can lead to a refusal even when the worker is otherwise qualified.
Our guide to sponsorship certificates sets out the practical side of this in more depth for employers handling their first few assignments.
Defined versus undefined CoS: which one do you need?
Sponsor guidance splits certificates into two categories, and choosing the wrong one is one of the most common early mistakes. A Defined CoS (DCoS) applies to workers applying for entry clearance from outside the UK, while an Undefined CoS covers in-country switches and other routes where the worker is already present.
Requesting a DCoS is not automatic. Sponsors submit a request through SMS specifying the SOC code, salary, working hours and proposed start date, and A-rated sponsors are generally required to request Defined CoS for entry clearance cases rather than relying on an allocation. Undefined CoS, by contrast, are usually drawn from an annual allocation set when your licence was granted or renewed.
Some sectors carry extra layers. Government Authorised Exchange placements go through Sponsor a Worker (SpAW) submissions rather than the standard SpUK workflow, and care worker sponsors assigning CoS under SOC codes 6135 or 6136 face additional validation on job descriptions and salary structures.
Before requesting or assigning, check:
- Whether the worker is applying from overseas (Defined) or switching in-country (Undefined).
- Whether your licence rating (A-rated) allows the volume and type of CoS you need.
- Whether the SOC code matches the actual duties, not just a convenient label.
- Whether the salary meets both the going rate for the SOC code and any route-specific threshold.
Our piece on sponsorship certificates walks through worked examples of Defined and Undefined requests if you want to see the distinction applied to real job scenarios.
Requesting, assigning and using a CoS: the practical workflow
Getting from “we want to sponsor this person” to a usable CoS reference follows a fairly fixed sequence, and skipping steps is where most delays happen.
- Confirm your sponsor licence is active and that you have authorised Level 1 or Level 2 users set up in SMS.
- Decide whether the case needs a Defined CoS (overseas applicant) or an Undefined CoS (in-country switch), based on the worker’s current location and route.
- For a Defined CoS, submit the request with the SOC code, salary, weekly hours and intended start date; for Undefined CoS, confirm you have allocation remaining.
- Once approved or allocated, assign the CoS in SMS with accurate job details, including PAYE reference where required for the role.
- Pay the CoS assignment fee and, for Skilled Worker sponsorship, the Immigration Skills Charge before or as part of assignment.
- Give the CoS reference number to the worker directly and confirm they understand the three-month window to apply.
- If an error is spotted after assignment, correct it promptly through SMS or contact UKVI to reclaim and reissue an invalid CoS rather than leaving inaccurate details on record.
Pro Tip: Build a short internal sign-off step, even just an email confirming the SOC code and salary against the job description, before anyone clicks “assign” in SMS. It takes minutes and catches most of the errors that later trigger refusals or compliance queries.
Timing matters here as much as accuracy. Assigning a CoS too early, before contract terms are finalised, often means the details drift out of line with reality by the time the worker applies. Our job-offer visa application guide covers how to sequence this alongside the worker’s own application steps, including what they will need once the UK has moved to eVisas rather than paper or card proof of status.
Fees and charges: CoS assignment and the Immigration Skills Charge
Two separate costs apply when you assign a CoS, and neither can legally be passed on to the worker.
The CoS assignment fee depends on licence type, with typical figures of £525 for most worker licences and £55 for short-term assignments. On top of that, employers sponsoring Skilled Workers normally pay the Immigration Skills Charge (ISC), a statutory levy intended to encourage investment in training resident workers.
| Sponsor size | ISC for first 12 months | ISC for each further 6 months |
|---|---|---|
| Medium or large sponsor | £1,320 | £660 |
| Small or charitable sponsor | Reduced rate applies | Reduced rate applies |
The Immigration Skills Charge can reach £6,600 over a five-year Skilled Worker sponsorship for a medium or large employer, a cost worth building into any hiring budget well before you assign a CoS.
Certain categories are exempt or pay reduced rates, and the exact schedule sits in the Immigration Skills Charge Regulations, which have been amended since they first came into force. Because rates change periodically, check GOV.UK directly before finalising a budget rather than relying on a figure from a previous hiring round.
Sponsor duties, record keeping and compliance risk
Assigning a CoS is the start of an ongoing set of obligations, not the end of one. Sponsors must keep specific records for each sponsored worker, and gaps here are a leading cause of compliance action.
- Keep recruitment evidence showing how and why the role was advertised and filled, where the route requires it.
- Maintain up-to-date contact details for each sponsored worker and report changes promptly.
- Report significant events through SMS: changes to job role or salary, unauthorised absences, early leaving dates or non-attendance.
- Retain evidence of right-to-work checks and salary payments consistent with what the CoS declared.
Failures here rarely come from deliberate wrongdoing. More often it is a missed reporting deadline or a salary that drifted below the threshold after a restructure, and either can trigger a compliance visit. Consequences range from a licence downgrade to suspension or revocation, and in serious cases the Home Office can require sponsors to reclaim CoS already assigned. You can check current sponsor licence status and CoS validity through the CoS checking system, and it is worth doing so periodically rather than only when a problem arises. Our guide on the role of a sponsor in UK visa cases covers the wider duty of care sponsors owe, much of which mirrors the standards expected under worker sponsorship.
Common mistakes and how to avoid them
Most refusals and compliance flags trace back to a small set of recurring errors, all avoidable with a bit of process discipline.
- Using the wrong SOC code, often because it is easier than matching the code to actual duties.
- Entering a salary that looks correct on paper but misses the going rate for that specific occupation.
- Assigning the CoS before contract terms, hours or start date are finalised.
- Leaving PAYE reference details incomplete or inconsistent with payroll records.
- Asking the sponsored worker to cover the assignment fee or Immigration Skills Charge, which sponsors must not do.
Pro Tip: Keep a standard job template for each SOC code you sponsor against, with salary bands checked against current going rates before every assignment. It turns a manual judgement call into a quick comparison.
If you catch an error after assignment, correct it in SMS without delay or contact UKVI to reclaim an invalid CoS rather than letting the worker apply on inaccurate information.
Timelines: how long each step takes and how long a CoS lasts
Once assigned, a CoS must be used within three months or it expires and cannot be reused. DCoS requests are not instant either: some are validated quickly through automated checks in SpUK, while others, particularly those needing extra scrutiny on SOC codes or salary, go to a caseworker and take longer.
Licence rating affects this too: A-rated sponsors generally see faster processing than those under closer monitoring. Because of this, assign the CoS only once you are confident the start date is realistic, factoring in visa processing time on top of the three-month usage window rather than assigning the moment a job offer is made.
When to get professional legal help with CoS matters
Some cases carry more risk than a straightforward assignment. Complex SOC code decisions, care worker sponsorship under scrutiny-heavy codes, ATAS clearance for research roles, or salaries sitting close to a threshold all benefit from a second, qualified pair of eyes before you commit to a CoS. Transitional skill and salary provisions can also shift eligibility in ways that are easy to miss without regular exposure to sponsor guidance, as practitioner commentary on recent RQF and salary threshold changes has noted.
A specialist immigration solicitor can check SOC and salary alignment against current thresholds, prepare DCoS requests correctly the first time, support sponsor licence applications and renewals, and represent employers where a refusal or compliance action needs challenging. Legal firms offer fixed-fee services and fast-track options for employers facing tight sponsorship deadlines.
An experienced view on getting CoS right the first time
Sponsors who treat CoS assignment as a formality tend to learn, the hard way, that it is a legal declaration with real consequences. The employers who avoid trouble are the ones who plan early: confirming SOC codes, salary bands and start dates well before the assignment stage, not after. A compliance-first habit in HR costs little and protects a licence that took real effort to obtain.
— michelle
How MNS Solicitors supports employers through CoS and sponsorship
Getting a Certificate of Sponsorship right the first time saves both money and the licence risk that comes with a rejected or flawed assignment. Every enquiry is handled directly by a qualified solicitor from the outset, not passed down to a trainee, with fixed pricing agreed before any work begins.
Employers turn to us for:
- An initial consultation to review a specific CoS or sponsor licence question before you commit.
- The urgent visa service when a sponsorship deadline is close and there is no room for delay.
- Broader support across settlement, appeals and judicial review when a compliance issue escalates beyond a single CoS.
If your organisation is preparing to sponsor a worker or facing a query over an existing CoS, book a consultation through our fees page and speak to a solicitor directly rather than working through the process alone.
Where to check official CoS guidance
For current fees, forms and rules, go to GOV.UK’s sponsorship guidance for certificates of sponsorship and the Immigration Skills Charge page. Both are updated as rates and requirements change, so check them directly before finalising a budget or a request.
This article is general information, not a substitute for advice from a qualified lawyer. Consult a qualified legal professional about your own circumstances before acting on anything here.
Sources
FAQ
How much does a CoS cost for a three-year sponsorship?
The cost combines the CoS assignment fee, typically £525 for most worker licences, with the Immigration Skills Charge. For a medium or large sponsor, the ISC alone runs to £1,320 for the first 12 months plus £660 for each further six-month period, so a three-year sponsorship adds several instalments on top of the assignment fee.
What is the current process for requesting a Defined CoS?
A Defined CoS is requested through SMS by specifying the SOC code, salary, working hours and start date, and A-rated sponsors are generally required to make this request for entry clearance cases rather than drawing from a standing allocation. Requests go through validation checks on the SOC code and salary before approval.
How long does it take to get a Certificate of Sponsorship in the UK?
Processing varies: straightforward Undefined CoS assignments from an existing allocation can be near instant, while Defined CoS requests may need caseworker review when extra checks apply. Sponsors with an A-rated licence generally see faster turnaround than those under closer monitoring.
How long is a Certificate of Sponsorship valid once assigned?
Once assigned, the worker must use the CoS reference in their visa application within three months. After that window, the certificate expires and cannot be reused, so the sponsor would need to assign a new one.
Can MNS Solicitors help with sponsor licence and CoS problems?
Yes, MNS Solicitors supports employers with sponsor licence applications, CoS requests and compliance queries, with every case handled by a qualified solicitor from the start. An initial consultation is a practical first step if you need a specific CoS or licence issue reviewed.
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