The Australian Taxation Office (ATO) provides guidance on what constitutes a tax invoice, including:

1.    The supplier's identity.

2.    The supplier's Australian Business Number (ABN).

3.    A description of what is sold or provided.

4.    The extent to which sale (the amount) contains Goods and Services Tax (GST).  Typically it is one eleventh of the gross amount - in this case the narration 'total price includes GST? would be appropriate.  Alternatively, state the amount of GST included.

5.    The date the tax invoice is issued.

6.    The recipient's name.

7.    The recipient's address.

8.    The recipients ABN.