UK Certificate of Sponsorship Explained: Read Your CoS

A UK Certificate of Sponsorship (CoS) from Nigeria is a digital reference number, not a paper certificate. Your licensed employer assigns it through their own Home Office account, and it costs you nothing — the employer pays £239. This page decodes what is actually on that reference, which type you need applying from Lagos or Abuja, and the one fact that turns this page into anti-scam armour: since 9 April 2025, asking you to pay for a CoS is a compliance breach, not a fee.

What’s on your CoS: the fields that must match your application

In short: your CoS carries a sponsor licence number, your SOC code and salary, job title, start date and work address, and whether your sponsor certifies your maintenance funds. Every field must match your visa application — a mismatch reads as a refusal risk, not a typo you fix later. Source: gov.uk, “Certificate of Sponsorship.”

• Sponsor licence number — ties the CoS to your employer’s entry on the gov.uk register. No matching licence, no genuine CoS.
• SOC code and going rate — the going rate / SOC code pairing sets your salary floor. Your CoS salary must clear that rate. It is a separate test from the general salary threshold £38700 when the rule came in, £41,700 from 2026 — which is occupation-independent and applies on top.
• Job title, start date, work address — must match the offer you actually accepted, not a generic template.
• Maintenance certified? — a checkbox confirming your sponsor certifies your funds. Checked, you skip separate savings proof.
• CoS type — Defined or undefined, decoded below.

You usually receive these details by email, not a downloadable file — a genuine CoS is a record inside your employer’s system, referenced by number. Read every field against your written offer before you apply. A mismatch here is grounds for refusal, and correcting it after submission is far harder than checking it first.

Defined vs undefined CoS: which one you need from Nigeria

In short: a defined CoS is for entry clearance from outside the UK — the type almost every applicant in Lagos or Abuja needs. An undefined CoS is for switching status inside the UK. Getting you a defined CoS requires your sponsor to request Home Office authorisation first, a step undefined CoS skips. Source: gov.uk, “Certificate of Sponsorship: Overview.”

Applying for entry clearance from Nigeria, your CoS type should read defined. Your sponsor cannot simply assign one from a general pool — they request authorisation through their Sponsorship Management System account, and the Home Office typically clears it within a working day. That is an extra step, and it is exactly why a defined CoS can take a little longer to land than the undefined type, which draws instantly from a sponsor’s existing annual allocation.

If your employer tells you your CoS is undefined while you are applying from outside the UK, ask why before you submit. An undefined CoS used for an entry-clearance application is a mismatch of its own, and it can cost you the application.

Who pays for a CoS — and why paying for one is a red flag

In short: the employer pays the CoS fee (£239) and, on most routes, the Immigration Skills Charge (£364–£1,000 a year). Since 9 April 2025, passing either cost to the worker is banned outright — a compliance breach the sponsor can lose its licence over. Source: gov.uk sponsorship guidance.

The CoS cost sits with the employer, in full, on every route. So does the Immigration Skills Charge on most routes — exempt only on Health and Care Worker — and the sponsor’s own licence fee, renewed roughly every four years. None of it is yours to pay.

Source: gov.uk sponsorship guidance, checked July 2026. The ₦ column shows what the employer absorbs, not a bill you receive — your share of every line is ₦0. ₦ figures are this site’s own conversion, not an official naira price: ₦1,540/$ (July 2026 card rate) at $1.296/£, giving roughly ₦1,996/£ on 24 July 2026.

Since 9 April 2025, that has been a formal rule, not just good practice: a licensed sponsor cannot recover the CoS fee, the Immigration Skills Charge, or the sponsor-licence fee from a sponsored worker. Breaching it is a compliance failure the Home Office can act on, up to suspending or revoking the sponsor’s licence — which puts every worker they sponsor at risk, not just you.

That is why any request for money “for the CoS” is a red flag, not a negotiation. A real UK Certificate of Sponsorship from Nigeria is assigned by a licensed sponsor after a genuine job offer, through their own Home Office account — never sold, never emailed as a PDF for a fee, never offered “with maintenance” for ₦2–8 million on WhatsApp. Verify any employer free on the gov.uk sponsor licence register — some job ads still call it the “sponsor list,” same free lookup — cross-check the pattern against the fake-job-offer scam, and if you have already paid, see avoid visa scams in Nigeria.

What you actually pay: the visa fee, plus the IHS unless you are on the Health and Care route. UKVI bills both in US dollars, so a plain naira card declines at that screen. Pay the IHS first, keep its reference number, then pay the fee — the full decision tree.

Older job ads still call this a “tier-2 CoS.” Tier 2 (General) was renamed Skilled Worker in December 2020 — the CoS mechanics on this page didn’t change, only the name did.

How to check your CoS reference is genuine

In short: two free checks confirm a CoS is real — the sponsor’s licence on gov.uk, and the CoS fields against your written offer. Both cost ₦0 and take about 15 minutes. Source: gov.uk, “Register of licensed sponsors: workers.”

1. Search the sponsor’s exact legal name on the gov.uk sponsor licence register and confirm an A-rating for your route.
2. Match the CoS reference’s job title, salary, start date and work address against your written offer.
3. Confirm the CoS type reads Defined if you are applying from outside the UK.
4. Apply before it expires — a CoS is valid for 3 months from assignment, then it is unusable.

Confirming your Skilled Worker eligibility or the Health and Care route comes before any of this — a genuine CoS only follows a genuine job offer on the right route. New to a term on this page? The visa glossary defines each one in a line.

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