Changing the use of a building / business premises, may or may not need planning permission, it depends if the proposed change meets certain requirements.
You will not need approval if the Current Use is compatible with the New Use under Exempt development:
Specific information about Changes of Use that are Exempt development can be accessed here:
View more details Exempt Development
If the proposal doesn't qualify as Exempt Development, you may be able to apply through Complying Development or a Development Application – see below for more information
A Complying Development Certificate may be issued for your Change of Use if the proposal meets all of the relevant development standards.
You can use the Commercial and Industrial Alterations Code (Part 5, Division 1, Subdivision 2) to check whether your proposal is complying development.
If your proposal does not meet all of the standards you must lodge a Development Application.
If your proposal does not qualify as Complying Development, you will need to lodge a Development Application with Council.
The NSW Department of Planning, Industry and Environment has a useful guide to the DA process.