If you are not registered for GST
If your business is not required to be registered for GST and you have chosen not to register:
Don’t collect GST on your sales or claim GST credits on your purchases. Your business issues normal invoices – it must not issue tax invoices. Normal invoices don’t include the words ‘tax invoice’ or indicate that the invoiced amount includes GST.
Do claim the full cost of your business purchases (including any GST) as a tax deduction on your income tax return.
If you receive an invoice for goods or services you have purchased from someone who is not registered or required to be registered for GST, it is not a tax invoice and you cannot claim a GST credit for the GST included in the price of those goods or services.
If you are not registered for GST you cannot issue tax invoices or claim GST credits on your purchases.