GST Levied on Pf and Esi under Labour Supply Contract

If A Supplier provide labour supply under an agreement,

Two types of Query are as under:-

a) if Supplier issue a invoice with Labour charges including pf and esi so gst is leviable or not on total bill amount including pf and esi.

b) if supplier issue seprate invoice for labour charges and seprate invoice for pf and esi, so gst is levied or not on pf and esi invoice.

Please suggest me with proper Section and guidelines.

Thanks.