How to Add GST to an Invoice

Adding GST to an invoice means calculating 10% of the GST-exclusive subtotal and clearly showing it on the document. Only businesses registered for GST should add GST to their invoices — and the invoice must be labelled "Tax Invoice" once GST is included.

To add GST to your invoice: 1. Confirm you're registered for GST (required once turnover hits $75,000/year) 2. List each item with its GST-exclusive price (or mark it as GST inclusive) 3. Subtotal the GST-exclusive amounts 4. Multiply the subtotal by 0.10 to get the GST amount 5. Show the GST on its own line: "GST (10%): $X" 6. Add the GST to the subtotal to get the total amount payable 7. Label the document "Tax Invoice" at the top 8. Include your ABN — it's mandatory on tax invoices

Some items are GST-free (basic food, education, health services) or input-taxed (residential rent, financial services). Don't add GST to those lines, but you can still include them on the same tax invoice. InvoiceSonic calculates GST automatically once you tick the "GST registered" toggle.