Working more hours for the same employer

hi,

I am a Tier 2 holder, in my Cos it states that I work up to 37.5 hours a week,

I am planning to ask HR to allow me to work more hours (e.g 20 more hours / week)
is that legal? and will I need to change my COS?
and what do I need to provide when I extend my visa?

Thank you,

Where the migrant is paid hourly, the appropriate salary consideration will be based on earnings up to a maximum of 48 hours a week, even if the migrant
works for longer than this. For example, a migrant who works 60 hours a week for £10 per hour would be considered to have a salary of £24,960 (10x48x52) and not £31,200 (10x60x52). This migrant would therefore not be awarded points for appropriate salary.

The above is excerpt from an old guidance for sponsors (07/18), so check the latest version.

If your are planning to work extra hrs to meet certain requirements, then take above into consideration. Your employer should inform change of hours via SMS system.