Early T2 extension implications

[Franky_fun]

My original T2 visa was started in Feb 2019 and will expire in Jan 2021. My company has agreed to extend my contract to Dec 2021. We have also started to prepare the COS and the extension application.

I am considering to get a mortgage but the requirement from the bank is that my visa needs to have at least 1 year remaining. Therefore, I would like to get the COS start date dated as 30 Sep so that I can apply within July.

Although my understanding is that it should not have major implications, there are some sayings that if the new visa get approved and started in Sep (4 months before the original expiry date), the overlap will shorten the maximum 6-year tier 2 duration by 4 months accordingly. Is that really true?

Idon’t think it makes sense as it won’t change the total period of time I can stay in the UK with an early extension, yet I would love to find out.