The Certificate of Sponsorship is the single document that connects your Sponsor Licence to a specific worker's visa application. Without a valid CoS, your candidate cannot apply for a Skilled Worker visa — regardless of how strong their qualifications are or how urgently you need them. This guide covers how the CoS system works in 2026, the difference between Defined and Undefined CoS, how to assign one correctly, the SOC code and salary rules, and the errors that cause CoS assignments to be rejected or visa applications to fail.
What Is a Certificate of Sponsorship?
A CoS is not a physical document — it is an electronic record created by the employer through the Sponsor Management System (SMS). It contains the details of the job, the salary, the SOC code, the worker's personal information, and the start date. When you 'assign' a CoS to a worker, UKVI generates a unique CoS reference number that the worker uses to make their visa application.
Each CoS costs £525 for the Skilled Worker and other main Worker routes. The fee is payable when the CoS is assigned, and it is non-refundable even if the CoS is later cancelled or the visa application is refused.
Defined vs Undefined CoS
The most common mistake: using an Undefined CoS for a worker outside the UK, or requesting a Defined CoS when the worker is already in the UK. Getting this wrong delays the visa application by weeks.
How to Request a Defined CoS Allocation
The Defined CoS Workflow
Step 1: Log into the Sponsor Management System
Using your Level 1 User credentials.
Step 2: Submit a CoS allocation request
Specify the number of Defined CoS you need. Include the job details, SOC code, salary, and worker's nationality.
Step 3: UKVI reviews the request
They check the role is genuine, the salary meets the threshold, and the SOC code is correct. This typically takes 1–5 working days.
Step 4: Allocation granted
The CoS allocation appears in your SMS account. You can now assign it to a specific worker.
Step 5: Assign the CoS
Enter the worker's personal details, passport number, qualifications, and start date. Pay the £525 fee. A unique CoS reference number is generated.
Step 6: Share the reference number with the worker
They use this to make their Skilled Worker visa application.
SOC Codes — Getting Them Right
Every CoS must reference a Standard Occupational Classification (SOC) 2020 code. The SOC code determines the 'going rate' for the role — the minimum salary UKVI will accept for that occupation. Choosing the wrong SOC code is one of the most common reasons CoS assignments and visa applications fail.
Three SOC Code Mistakes That Cause Failures
1. Using an old SOC 2010 code — The UK switched to SOC 2020 in April 2024. Old codes are no longer valid.
2. Picking the closest-sounding code rather than the correct one — A "software developer" is SOC 2134, not SOC 2135 (IT business analyst). The going rates differ.
3. Inflating the SOC code to justify a lower salary — Assigning a senior-level code to a junior role to meet a higher going rate is fraud, and UKVI audits for it.
Salary Rules for CoS Assignment
The salary on the CoS must meet both the general salary threshold and the going rate for the SOC code:
2026 Salary Thresholds
• General threshold: £38,700 per year (for most Skilled Worker roles)
• New entrant threshold: £30,960 per year (for workers under 26, switching from Student/Graduate visa, or in certain postdoc roles)
• Going rate: varies by SOC code — check the Immigration Rules Appendix Skilled Occupations
• Immigration Salary List roles: the higher of £30,960 or 80% of the going rate
The salary on the CoS must be the higher of the applicable threshold and the going rate. Guaranteed base salary only — overtime, bonuses, tips and commission do not count.
What Happens After You Assign a CoS
Once assigned, the CoS is valid for 3 months. The worker must submit their visa application within that window. If they don't, the CoS expires and you must assign a new one (with another £525 fee).
A common timing issue: employers assign the CoS before the worker is ready to apply, then the 3-month window closes before documents are gathered. Coordinate timing with your candidate before assigning.
Cancelling and Withdrawing a CoS
When You Can Cancel
• The worker decides not to take the role
• The visa application is refused
• You made an error and need to re-assign
• The worker does not start within the expected timeframe
Cancelling a CoS does not refund the £525 fee. The CoS allocation may be returned to your account, but the fee is gone. This is why accuracy matters the first time.
Common CoS Errors and How to Avoid Them
Seven Errors That Cause Problems
1. Salary on CoS doesn't match the employment contract
2. Wrong SOC code — usually from guessing rather than checking the ONS lookup tool
3. Defined/Undefined mix-up — using the wrong type for the worker's location
4. Start date unrealistic — set too early for visa processing, or too far out
5. Worker's name doesn't match passport exactly — middle names, spelling variations
6. Missing qualifications — the CoS must reference qualifications that meet RQF Level 3+
7. Forgetting to pay the ISC — the Immigration Skills Charge must be paid at CoS assignment, or the CoS is not valid
CoS and the Immigration Skills Charge
The ISC is due at the point you assign the CoS, for the full duration of the visa. For a 3-year Skilled Worker visa at large-sponsor rates, that is £3,960 payable immediately alongside the £525 CoS fee. The combined upfront cost of assigning a single CoS is therefore £4,485 for a large sponsor on a 3-year visa — before the worker has even applied.
How Recruitroo Handles CoS for UK Employers
Recruitroo prepares and validates CoS assignments before they hit the SMS. Our platform checks the SOC code against the role description, validates the salary against both the general threshold and the going rate, confirms Defined vs Undefined selection, and flags any data mismatches between the contract, the CoS and the worker's documents. Our clients see near-zero CoS errors and no wasted £525 fees.
Need help with Certificate of Sponsorship assignments?
Tell us the role and the worker's situation. We'll confirm the correct SOC code, salary threshold, and CoS type — and handle the assignment through our platform.
Get a QuoteSee Client StoriesThis guide reflects UK Certificate of Sponsorship rules as of May 2026. SOC codes, salary thresholds and CoS fees are subject to change — always verify against current Immigration Rules.