What has to be on an Australian tax invoice?

The words Tax Invoice, the seller's identity and ABN, the date, a description of what was sold, and either the GST amount or a statement that the total includes GST. Over $1,000 it also needs the buyer's identity or ABN. This is set by the ATO, not by convention.

Can I just calculate GST as one eleventh of the total?

Only when everything on the invoice is taxable. Some goods and services are GST free, and an invoice can mix both, in which case the GST is not a fixed fraction of the total. Read the printed figure.

How long do I need to keep invoices?

Five years in Australia, and electronic copies are acceptable. You do not need the paper if you have a legible digital copy.

Guide

Pulling GST and totals off Australian tax invoices

Australian tax invoices have rules about what must appear on them, which makes them more predictable than most documents. Here is what you can rely on, and the one thing that catches everybody.

Short answer

A valid Australian tax invoice must show the supplier's ABN, the GST amount or a statement that the total includes GST, and the words Tax Invoice. Those are reliable. The total is not, because the largest number on the page is often a subtotal.

What must be on a valid tax invoice

The ATO requires specific fields, which is useful, because it means you can count on them being present.

The words Tax Invoice: Usually at the top, and a reliable way to tell an invoice from a quote or a statement.
The seller's identity and ABN: An ABN is eleven digits, often written in a 2-3-3-3 grouping. That format is distinctive and easy to find.
The date it was issued: Format varies, so do not assume day-month-year.
What was sold: Description, and quantity where relevant.
The GST amount: Either shown separately, or a statement that the total includes GST. For sales over $1,000 the buyer's identity or ABN is required too.

The mistake that costs people money

Never take the largest number on the page as the total.

On an invoice with a credit applied, the subtotal is larger than the amount payable. On an invoice showing a running account balance, the balance can be larger than this invoice. On a credit note the correct figure is negative, and taking the absolute value quietly reverses the sign of the transaction.

Read the label, not the size. Amount payable, Total due, and Balance due mean the thing you want. Subtotal and Total excluding GST do not.

Where GST gets complicated

Not everything has GST on it: Basic food, most health services and some education are GST free. An invoice can legitimately show a total with no GST at all, so a rule that assumes ten percent will produce wrong numbers.
Mixed invoices: A single invoice can contain both taxable and GST free items. The GST is then not ten percent of the total and you cannot calculate it, you have to read it.
Overseas suppliers: Software billed from overseas may show no GST, or may show it in another currency. Solven's own Google Workspace invoices are issued by Google India in rupees with Indian GST on them.

What to capture for BAS time

If the point of the exercise is your quarterly BAS, the useful columns are: supplier, ABN, invoice date, invoice number, total including GST, and GST amount.

Keep the GST amount as printed rather than calculating it, for the reasons above.

Records must be kept for five years, and an electronic copy is acceptable. A folder of properly named PDFs plus a spreadsheet is a perfectly good record.

Common questions

What has to be on an Australian tax invoice?: The words Tax Invoice, the seller's identity and ABN, the date, a description of what was sold, and either the GST amount or a statement that the total includes GST. Over $1,000 it also needs the buyer's identity or ABN. This is set by the ATO, not by convention.
Can I just calculate GST as one eleventh of the total?: Only when everything on the invoice is taxable. Some goods and services are GST free, and an invoice can mix both, in which case the GST is not a fixed fraction of the total. Read the printed figure.
How long do I need to keep invoices?: Five years in Australia, and electronic copies are acceptable. You do not need the paper if you have a legible digital copy.

Solven builds custom software and automation for Australian businesses. If you have a job like this that no tool quite fits, that is the work we do.

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