Some little tweaks are needed for GST, ABNs, and Invoices need to be called Tax Invoices.

Found these ones someone had already made. They look nicer than the standard Invoices too :)

• Australian business invoicing with Gnucash

Some alternate info on the GNUCash Wiki FAQ:

• §How do I change "Invoice" to "Tax Invoice" as required in Australia?

On Linux just chuck those .SCM files in ~/.local/share/gnucash