Tier 2 Extension application query

[Immigrant101]

Dear all ,

Thank you very much for your support and help in my previous applications.
I have just few questions regarding tier 2 extension application.

1-Which application form do i need to .submit
2: what is the fee for extension application
3: i saw one tier 2 extension form where there was no fee requirement for tier 2 extension.
4: will my employer need to apply for new CoS and what will be the process for CoS allocation for extension applications?
5: what is the maintenance requirement?
6: is it a must to submit pay slips with extension applications? if yes then how many months? my first visa was granted for 2 years now can i apply for 4 more years visa?

please reply urgently.
Thanks