Invoice
An invoice is issued by a seller requesting payment for goods or services purchased.
To claim GST on a purchase over $82.50, including GST, you need a tax invoice. See Issuing a tax invoice on the ATO website for further information.
Purchase order
A purchase order is a request to purchase specified goods or services for an agreed price from a seller. A purchase order only becomes a commitment once it is accepted by the seller.
When to issue a purchase order?
Issue a purchase order when a seller requires a formal commitment to purchase the goods or services before delivering the goods or providing the services.
Note: Not all purchases require the issue of a purchase order. Many purchases are made under other arrangements, such as a contract, and include phone and internet services, and bank fees and charges applied to an account.
Quote
A quote is issued by a seller to provide the full details and pricing of the goods or services to be provided to a potential buyer.
When to issue a quote?
A quote is issued when the goods or services being sold are complex or if requested by a potential buyer.