Certificate of Sponsorship (CoS): Expert Legal Guidance from London Immigration Solicitors

For any foreign national seeking to work in the UK under a sponsored route, the Certificate of Sponsorship (CoS) is the single most important document. It is not an actual paper certificate but a unique electronic reference number issued by a licensed UK employer, signifying that they have formally allocated a skilled role to you. Without a valid CoS, a visa application cannot be submitted. This page serves as your comprehensive guide to the CoS, its purpose, and the critical role it plays in your immigration journey. At Conroy Baker Ltd., our specialist Certificate of Sponsorship (CoS) Immigration Solicitors in London provide proactive legal services to ensure this crucial step is executed flawlessly.

A Certificate of Sponsorship (CoS) is the critical link between your job offer and your sponsored worker’s UK visa. It’s not a paper certificate, but an electronic record generated in the Sponsor Management System (SMS), issued by a licensed UK sponsor. The Home Office uses the data on the CoS to decide whether to approve or refuse a visa application.

One error – from the wrong SOC code to an incorrect salary figure – can result in visa refusal, delays of several months, and even compliance action against your UK Sponsor Licence.

At Conroy Baker Ltd., our London-based immigration experts provide end-to-end CoS management – from pre-assignment checks, allocation requests, and SMS assignment, to compliance reporting and audit readiness – so your hires are never delayed, and your licence is never at risk.

A CoS is more than an administrative step – it’s the legal authorisation to employ a foreign national under a sponsored visa route.

Without a valid CoS assigned to the worker, you cannot lawfully proceed with the hire.

Confirms that the vacancy meets the Home Office’s skill and salary thresholds, including minimum going rates for the occupation code.

Every Certificate of Sponsorship (CoS) assignment is logged in SMS, forming part of your audit trail. Any inaccuracy risks your Sponsor Licence.

Robust CoS management is a key Home Office expectation during compliance audits. Mistakes can lead to licence suspension or revocation.

For an individual, the Certificate of Sponsorship (CoS) is the definitive green light to apply for a visa. It proves that a legitimate, licensed UK employer has a confirmed role for you. Without it, your visa application cannot proceed. It is crucial for applicants to verify that all the information on their CoS is accurate and consistent with their job offer letter. Our legal team can assist in reviewing your CoS details before you submit your visa application.

Mastering the Certificate of Sponsorship (CoS) process is fundamental to fulfilling your sponsor duties and avoiding sanctions from the Home Office. Our service is designed to help you with every critical function:

No CoS = no sponsored visa application.

Proves a Genuine Job Offer

Discrepancies between the CoS and your employment contract are a common reason for visa refusals.

We routinely identify and fix these issues before they reach the Home Office:

Assigning a code that doesn’t match job duties invalidates the CoS. We align your role with the correct SOC based on detailed duty analysis.

Miscalculations, especially for part-time roles or those with allowances, can result in underpaying against the visa rules. We confirm all salaries meet the latest thresholds and going rates.

Job titles, start dates, hours, and work locations must match across the CoS, contract, and offer letter — we ensure 100% alignment.

Changes must be reported within 10 working days; we build reminders and reporting processes for your HR team.

Running out of CoS allocation delays recruitment. We forecast needs and submit timely allocation increase requests with evidence.

Errors in SMS entries are common without proper training; we either manage the SMS for you or train your team.

• Defined CoS: For Skilled Worker visa applicants applying from outside the UK; must be requested and approved in SMS before assignment.
• Undefined CoS: For Skilled Worker visa applications from within the UK (extensions, changes of employment); issued from your annual allocation.

Assigning the wrong type can cause application rejections and weeks of lost time. We ensure the correct type is used, request Defined CoS quickly when needed, and manage allocations so you never run out.

Sponsors must report via SMS within 10 working days if:

• The worker does not start on the expected date.
• The worker is absent without permission for 10+ consecutive days.
• The worker leaves employment or is dismissed.
• The worker’s job title, duties, salary, or work location changes.

Missing these deadlines can lead to sponsor licence downgrades, suspensions, or civil penalties.

• Pre-check & alignment: 24–48 hours once documents are provided.
• Defined CoS request: Same day to 3–5 working days (Home Office dependent).
• Undefined CoS assignment: Same day once details are ready.
  Urgent hires can be prioritised.

We handle the process end-to-end so you avoid costly mistakes and time delays:

• Confirm SOC code, job duties, and skill level.
• Verify salary meets visa thresholds & going rate.
• Cross-check start date, hours, and location against contract.

• Forecast allocation needs based on hiring plans.
• Prepare evidence and submit allocation increase requests.

• Act as your appointed Level 1 User or guide your team step-by-step.
• Enter data with zero errors and issue CoS securely to the applicant.

• Ensure the offer letter, contract, job description, and qualifications match the CoS exactly.

• Set up workflows for the 10-day reporting window for any changes
• Train your HR team to meet SMS reporting requirements.

• Conduct internal file audits.
• Maintain both digital SMS records and physical HR files for each sponsored worker.