Reduce length of assigned CoS

Hello there

My employer has assigned me a CoS for 4 years, however I only want a visa for 2 years.

I'd like to reduce the length as it will reduce the Visa costs significantly.

Because the CoS has already been assigned, am I able to change the length?
Is this something that can be done through sponsorship notes, and if so will I received a refund when I submit my application and pay the IHS etc - as I assume it would still charge me for 4 years.

Or does my employer need to withdraw the assigned CoS and create a new one?
If they did this, would they be refunded the immigration skills charge on the withdrawn CoS?

Any help appreciated!

Many thanks,
Sarah

Only minor changes can be made in a CoS by sponsor notes after it has been assigned and I don't believe that the reduction of the work period from 4 to 2 years falls in this category but do ask your sponsor to have this confirmed by phoning or emailing the UKVI employer helpline. If they confirm the CoS should be withdrawn and a new one assigned for the shorter work period.

The ISC the sponsor paid for the withdrawn CoS will be refunded, see p9:
https://assets.publishing.service.gov.u ... gov-uk.pdf

The cost of the withdrawn CoS (£199) will not be refunded.