What is a Certificate of Sponsorship?

A unique reference number a UK employer with a sponsor licence assigns to you when offering you a skilled job. Like the Student visa CAS, you don't submit the CoS document itself — you enter the reference number in your visa application and UKVI looks up the full record directly with the employer.

How long is a CoS valid?

Three months from the date of assignment. You must apply for your Skilled Worker visa within this window. If the CoS expires unused, the employer needs to assign a new one — and that may not be straightforward if their licence quota is constrained.

Can my employer just give me a CoS?

Only if they hold a Home Office sponsor licence at the relevant rating, have annual quota available (or you're exempt from quota), and the role meets the Skilled Worker criteria — eligible occupation code, salary at or above threshold, genuine vacancy.

Certificate of Sponsorship (CoS) for UK Skilled Worker Visa

TL;DR

A Certificate of Sponsorship (CoS) is the unique reference number your UK employer assigns when sponsoring you for a Skilled Worker visa. It's valid for 3 months and ties together the role, salary, and occupation code that UKVI checks. You apply within 3 months of CoS assignment; the visa is refused if you apply after the CoS expires.

What is a CoS?

The CoS is a digital record your sponsoring UK employer creates in the Sponsorship Management System (SMS), identified by a unique reference number. The CoS contains:

Your details — name, date of birth, nationality, passport number
Job details — job title, SOC (Standard Occupational Classification) code, salary, hours per week, working pattern
Start and end dates of the employment
Sponsor details — employer name, sponsor licence number, address
Maintenance certification — whether the sponsor will certify your £1,270 maintenance (so you don't need to evidence it separately)
Cooling-off references — whether you've previously held UK sponsorship that's now ended

UKVI looks up the live CoS record using the reference. You don't upload the CoS document itself.

Who can issue one?

Only employers with a current UK sponsor licence at the relevant rating. To check whether a prospective employer can sponsor:

Search the register of sponsors — published by the Home Office, updated daily
Confirm they hold the Worker route licence (not just Student or Temporary Worker)
Verify their rating is A-rated (B-rated sponsors can issue CoS but with restrictions)

Some sponsors hold a defined annual quota for "Defined CoS" (used to sponsor a worker from outside the UK who hasn't previously held a Skilled Worker visa). Others operate Undefined CoS (in-country switching, extensions). The distinction is technical but matters for timing.

How long does it take to get one?

Timing varies enormously by employer:

Established sponsors with HR teams — 1-2 weeks from job offer to CoS in hand
Smaller employers new to sponsorship — 4-8 weeks
Sponsors using SMS for the first time on you — additional checks may add weeks

Don't sign a flat or commit to a UK move until your CoS is assigned. Do not buy non-refundable flights or pay deposits.

Common issues

Salary at or above threshold — for 2026, general minimum is £38,700 or going rate for the SOC code, whichever is higher
SOC code mismatch — must accurately reflect the actual role; UKVI compliance visits look for fake SOC assignments
Late assignment — sponsor delays mean your CoS may be valid only briefly before you must travel and apply
Sponsor licence revoked between CoS assignment and visa decision — the visa is refused
Genuine vacancy test — UKVI checks the role exists for legitimate business reasons; "ghost roles" created to facilitate immigration are refused

How to apply for the visa with a CoS

Receive the CoS reference number from your sponsor (typically by email)
Start the Skilled Worker visa application within 3 months of the CoS assignment date
Enter the reference; the application form pulls in the CoS data
Submit supporting documents (passport, English language evidence, maintenance funds if not certified, TB test if applicable, qualifications if listed on the CoS)
Pay the visa fee + IHS, attend biometrics, await the decision

Decision time: 3 weeks standard from outside the UK, 8 weeks from inside, faster on priority service.

What if my application is refused?

If the visa is refused after CoS assignment:

The CoS is "used" — your sponsor needs to assign a new one for re-application
For some sponsors with limited quota, this is genuinely difficult
For administrative-error refusals, administrative review may be faster than re-applying

If the refusal is sponsor-related (licence issue, compliance breach), look for an alternative sponsor before re-applying.

Bundling

You don't bundle the CoS itself. Bundle your supporting documents:

Passport scans
English language certificate (or qualifying degree evidence)
Maintenance funds bank statements (if your CoS doesn't certify)
Qualification certificates if your CoS lists them
TB test if from a listed country

Use our Bundler to merge these in canonical UKVI order — passport first, then qualifications, then financial. Run our Checklist generator for the complete Skilled Worker list tailored to your specific situation.