Certificate of Sponsorship UK
Expert guidance on assigning Certificates
of Sponsorship UK to your overseas workers.
OISC Level 3 regulated advisers supporting
UK employers through every step.
What is a Certificate of Sponsorship UK?
A Certificate of Sponsorship (CoS) is not a
physical document it is a virtual record
in the Home Office database that a licensed
sponsor assigns to a worker they wish to employ.
The CoS contains key information about the job
role, salary, and the worker being sponsored.
The worker uses the CoS reference number as
part of their visa application.
Each CoS is valid for 3 months from the date
of issue. Once assigned, the sponsor takes full
responsibility for ensuring the worker complies
with their visa conditions.
Two types of Certificates of Sponsorship UK
📋 Undefined CoS
An Undefined CoS is assigned to a
worker who is already in the UK and
applying to stay (leave to remain).
Sponsors receive an annual allocation
of Undefined CoS. If allocation runs
out, sponsors must apply for more.
Processing time: Up to 18 weeks.
Priority service available: 5 working
days for £200.
📋 Defined CoS
A Defined CoS is assigned to a worker
who is applying for entry clearance
from OUTSIDE the UK.
Sponsors must apply for a Defined CoS
individually as and when needed
there is no annual allocation.
Processing time: Typically 1 working
day if straightforward.
Sponsor Responsibilities after Assigning a CoS
Once a Certificate of Sponsorship is issued,
the sponsor becomes fully responsible for
the actions of the sponsored worker.
Key responsibilities include:
• Ensuring all CoS details are accurate
and match the visa application exactly
• Monitoring the worker’s immigration
status and right to work
• Reporting any changes in circumstances
to the Home Office promptly
• Maintaining accurate HR records
for all sponsored workers
• Complying with all UKVI audit requirements
Non-compliance can result in suspension
or revocation of your Sponsor Licence.
Need Help Assigning a COS?
Our OISC regulated advisers will ensure your
Certificate of Sponsorship is assigned correctly
avoiding costly errors and delays.