Who is liable to issue a ‘tax invoice’ and how many copies are required to be issued?

Every registered person (other than a registered
person availing the benefit of composition or a registered
person supplying exempted goods or services) supplying
goods or services or both is required to issue ‘tax invoice’.
Invoice should be issued in triplicate in case of supply of goods.
The original copy is meant for buyer, duplicate for transporter
and triplicate copy for record of the seller. A registered person
under composition scheme or supplying exempted goods
or services shall issue a bill of supply instead of a tax invoice.