Certificate of sponsorship: what employers need to know

Accurately assigning a certificate of sponsorship is one of the most important steps in the skilled worker visa process. Even small errors — such as using the wrong occupation code or entering an incorrect salary — can lead to delays, refusals, or compliance action by the Home Office.

With recent changes to immigration rules now in force, employers must take extra care to ensure each certificate meets the latest requirements.

Our immigration solicitors act for employers nationwide, helping businesses manage sponsor licences, correctly assign certificates of sponsorship, and remain compliant with their reporting and record-keeping duties.

What is a certificate of sponsorship

A certificate of sponsorship (CoS) is an electronic document issued by a licensed employer to confirm that they are sponsoring a non-UK national for a specific job. It contains a unique reference number that the worker uses when applying for their visa.

The CoS does not guarantee a visa, but it is a legal prerequisite for all skilled worker applications. It confirms the job details, salary, working hours, and that the employer meets the Home Office’s sponsorship standards.

Defined and undefined CoS explained

There are two main types of CoS under the skilled worker route:

• Defined CoS – used for overseas applicants applying from outside the UK. Employers must request these individually through the sponsor management system (SMS).
   
• Undefined CoS – used for workers already in the UK who are extending their stay, switching visa category, or continuing employment with the same sponsor.

Employers must ensure they have enough undefined CoS allocations each year and apply for additional ones if needed. They should also make sure any certificates are assigned using the updated SOC 2020 occupation codes.

How to assign a CoS under the skilled worker route

Once the employer’s sponsor licence is in place, a CoS can be created and assigned through the SMS. The process typically involves:

• Confirming that the job is a genuine vacancy at the correct skill level — generally RQF 6 or above under the updated rules.
   
• Checking that the salary meets or exceeds the new general threshold of £41,700 or the going rate for that occupation. You may still be able to sponsor a worker for a job below graduate level if it’s included on the Immigration Salary List or covered by a transitional provision.
   
• Selecting the correct SOC code and inputting accurate job details, working hours, and start date.
   
• Ensuring the CoS start date aligns with visa processing timelines and employment readiness.
   
• Paying the applicable Home Office fee and, where required, the immigration skills charge.

The Home Office may audit employers to verify the accuracy of CoS information, so maintaining supporting documentation is essential.

Recent updates to CoS rules 

The Statement of Changes HC 1333 (which superseded HC 997) introduced several important updates that took effect on 22 July 2025:

• The general salary threshold for skilled workers increased to £41,700.
• Most eligible roles must now meet skill level RQF 6 or above.
• Occupation codes and going rates were updated across multiple sectors.
• Compliance guidance for CoS accuracy and reporting duties was strengthened, with greater scrutiny of sponsors’ HR and payroll systems.

Employers should review existing allocations, job codes, and salary offers to ensure ongoing compliance under the new framework.

Common mistakes employers make

Many issues arise not from intent but from administrative oversights. Frequent errors include:

• Selecting the wrong SOC code or using an ineligible occupation.
• Entering a salary below the new threshold or omitting allowances incorrectly.
• Assigning a CoS too early or with an inaccurate start date.
• Failing to report changes in role, hours, or salary through the SMS.
• Letting annual CoS allocations expire without renewal.

Any of these can lead to delays, refusal of the worker’s visa, or investigation of the employer’s sponsor licence.

How immigration solicitors help employers

Our immigration solicitors assist businesses in all aspects of the sponsorship process. We:

• Advise on job eligibility, SOC code selection, and salary calculations.
• Prepare and review CoS requests before submission.
• Manage undefined CoS allocations and renewal applications.
• Provide compliance training for HR teams using the SMS.
• Represent employers during Home Office audits or investigations.

By working with experienced advisers, employers can streamline recruitment and reduce the risk of errors that jeopardise their sponsor licence.

FAQs about certificates of sponsorship

Below, our immigration solicitors answer some of the most common questions from employers.

• What’s the difference between defined and undefined CoS?
  
  Defined CoS are used for new hires applying from overseas and require approval for each applicant. Undefined CoS cover extensions or in-country applications and are drawn from the employer’s annual allocation.
   
• How long is a certificate of sponsorship valid?
  
  A CoS must be used within three months of issue. If unused, it expires automatically, and a new one must be assigned.
   
• Can a CoS be amended after it’s been assigned?
  
  Minor corrections can sometimes be made before the visa application is submitted, but substantial errors usually require the CoS to be withdrawn and reissued.

Expert guidance from our immigration solicitors

Our immigration solicitors explain why early advice is key to avoiding costly mistakes under the new sponsorship rules.

Sanae Sahebjalal, specialist immigration solicitor, says:

“Assigning a certificate of sponsorship may seem routine, but small mistakes can have serious consequences. We regularly help employers correct errors before they cause refusals or compliance issues. Early advice saves time, money, and the frustration of starting over.”

Working with our immigration team ensures your business remains compliant and confident in meeting its Home Office sponsorship obligations. Get in touch to speak with our immigration solicitors.