As per this section,person registered under s.9(3) and s.9(4) need to issue tax invoice in respect of supplies received by him on which tax is payable under reverse charge .
Why is s.9(4) added here, as it clearly says " supplies in which supplier is unregistered ".This is s.9(3) and even if it is a supply covered in s.9(4) , as the supplier is unregistered ,it can be dealt in a manner same as s.9(3)
What is the need of mentioning s.9(4)