Hi bcpitt,
Thanks for reaching out to us with this, it's a great question.
It's always recommended to include your ABN when processing invoices or anything else relating to your customers and suppliers.
You can make sure your ABN is showing on your invoices by editing your invoices.
Go to Settings, then select Custom Form Styles, select the Standard template.
From there select the Content tab, and you will see the option for ABN there, make sure it is ticked and filled in, then you can select Save.
Let me know if you need a hand with anything else.
Kristian.
