Insight
Key Factors in Determining Work Dates on a CoS in the SW Route
Toby Way
|
21 Jan 2026
Choosing the correct work dates on a Certificate of Sponsorship (CoS) for a Skilled Worker visa is more than just selecting start and end dates. These dates impact visa validity, Home Office fees, and compliance with sponsorship duties.
In this blog, we’ll cover key factors to consider, common pitfalls to avoid, and tips to help you get it right the first time.
When Are the Work Dates Required?
For a defined certificate of sponsorship (CoS), you complete the relevant work dates section when you request it. For an undefined CoS you need to complete the section only when you assign the CoS to the migrant.
You will need to choose both work start and end dates when you input this information onto the CoS. The duration between these dates is significant as it both determines the Home Office costs and the length of the migrant’s visa.
Start Date
The relevant Home Office guidance states that the start date on the CoS must be ‘the date you expect the worker to start working for you’. This date can be difficult to estimate accurately, particularly if you are unfamiliar with the sponsorship processing times.
When you choose the start date, you must also choose a date which is within a 3 month period of the visa application to avoid the visa application later being invalidated.
End date
The duration between the work start and end dates is significant as it dictates both the length of the visa granted and the Home Office fees. See the cost comparison below which highlights a difference of over £3,000 between a 4-year and a 2-year visa for a small sponsor.
4 Year Visa Costs
CoS assignment costs:
Immigration Skills Charge: £364 x 4: £1456
CoS assignment fee: £239
Subtotal: £1695
Visa cost:
Home Office application fee: £1420
Immigration Health Surcharge: £1035 x 4: £4140
Subtotal: £5560
Total fees: £7255
2 Year Visa Costs
CoS costs:
Immigration Skills Charge (ISC): £364 x 2: £728
CoS Assignment fee: £239
Subtotal: £967
Visa Cost:
Application fee: £719
Immigration Health Surcharge: £1035 x 2: £2070
Subtotal: £2789
Total Fees: £3756
Still have questions?
Work Duration and New Entrants
If you are relying on the new entrant criteria to meet the visa salary requirements, it is paramount that you do not choose work dates that exceed the maximum period.
Typically this will be a 4 year period but you may need to deduct further time based on the migrant’s UK immigration history. If you exceed the relevant new entrant period, the migrant’s visa will be at risk of refusal.
Amending Work Dates on a CoS
Happily, the work dates can be changed even once you have assigned the CoS. For example, where the start date you have used has passed or is unrealistic, you can use the sponsor management system (SMS) to make a sponsor note to amend the work dates.
However, if you amend the work duration, complications may arise with the Immigration Skills Charge (ISC) and possibly the visa application payment.
If the revised work period extends beyond the initially stated dates, an additional ISC payment will be required (unless exempt), which may delay the visa application.
Further, once the visa application is caseworked, you will lose the start date flexibility and this can have serious consequences for the migrant’s sponsorship.
Note the Home Office guidance suggests that you can use the ‘report migrant activity function’ to amend work dates where the migrant has already submitted their visa application but in practice this is a risky strategy which often leads to unnecessary complications.
It is therefore very important to use the sponsor note function as soon as possible after the CoS is assigned and, at the latest, before the visa application is submitted, where amendments are required.
Late Start – 28 day rule
Once the visa has been granted the migrant must start work no later than 28 days after either the start date on the CoS or the start date on the entry clearance vignette (typically the day the visa was approved).
If you miss the 28 day deadline, you must report the late start through the SMS and must provide an ‘acceptable’ reason for the delay or terminate the sponsorship. Acceptable reasons for start date delays include:
Travel disruption caused by extreme events such as war or natural disasters;
Compelling personal or family circumstances such as bereavement;
Contractual notice periods. In this case, it is obviously best practice to find out the notice period before you assign the CoS so that you can change the start date accordingly.
Failure to report in these circumstances is a breach of sponsor licence duties and could lead the sponsoring business’s licence to be suspended.
Early Start Dates
Conversely, where a migrant’s visa has been granted and they start work before the start date on their CoS, you do not need to report this to the Home Office.
Key Takeaway: Carefully consider the CoS work dates—errors can lead to visa application delays, refusal, or even require the sponsoring employer to cancel the sponsorship before it starts.
If you have questions or require assistance with a certificate of sponsorship, please contact WestBridge Business Immigration for expert guidance.
Disclaimer
The information provided in these articles is for general guidance only and does not constitute legal advice. Immigration rules change frequently and individual circumstances vary, so you should always seek tailored advice from a qualified immigration lawyer before making any decisions. If you require professional support, our team would be pleased to assist you.
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