Main applicant future directions

Hi,
I applied for Tier 2 extension (change employer) in July 2020 and only received email of biometric reuse in the start of August 2020. My work start date is in mid of September 2020. Can I start work with the new employer if decision still not came?

My dependents' visas are valid till January 2021. Can my dependents apply for visa extension in September 2020 if my (main applicant) visa extension decision still pending? I am thinking about this due to health surcharge fees is due to increase in Oct 2020.

Thank you

Not any expert advice on my simple questions???

If you’ve applied for a Tier 2 or 5 visa and are waiting for a decision on your application

You can start work before your visa application has been decided if:

you’ve been assigned a Certificate of Sponsorship (CoS)
you submitted your application before your current visa expired and you show your sponsor evidence of this
the job you start is the same as the one listed on your CoS

If your application is eventually rejected as invalid or refused your sponsor will stop sponsoring you and you must stop working for them.

Thanks Vinny!

I would be thankful if some expert advice is given on my second query in my original post. Following is explained second query:

If main applicant is waiting for decision and have still valid CoS, can dependents apply for the visa extension? In the valid CoS, the maintenance is certified for main applicant and dependents.

Expert answer would be much helpful.