ABN Invoicing in AustraliaFormat, Placement & the 47% Withholding Rule
No ABN on your invoice?
A business client paying you more than A$75 (excluding GST) is generally required to withhold 47% of the payment if you haven't quoted an ABN. Quoting an ABN on every invoice avoids this entirely.
Everything you need to know about invoicing with an ABN in Australia: the format, where it goes on the invoice, how the checksum works, and exactly what the no-ABN withholding rule means for your cash flow.
What is an ABN?
An ABN (Australian Business Number) is an 11-digit number issued by the Australian Business Register (ABR) that identifies your business to the ATO, other businesses, and government agencies. It is not the same as being registered for GST - you can hold an ABN and trade without charging GST, as long as your GST turnover stays under A$75,000.
ABN vs GST registration - two separate steps
Getting an ABN doesn't automatically register you for GST. Registration is required once your GST turnover reaches (or you expect it to reach) A$75,000 a year, at which point you must register within 21 days and start issuing tax invoices. Read the full tax invoice requirements checklist once you cross that line.
Where the ABN goes and how it's formatted
Where it goes on your invoice
Your ABN sits in the supplier details block near your business name, at the top of the invoice - not buried in the footer or terms. For GST-registered suppliers it is one of the seven mandatory tax invoice details; for unregistered suppliers it is still worth showing, so clients don't have to withhold.
Invoices of A$1,000 or more also need the buyer's identity or ABN, in addition to your own.
ABN format & checksum
Display format
XX XXX XXX XXX
An ABN is always 11 digits and never starts with a 0. The last digits form a checksum under the ATO's published modulus-89 algorithm, which catches most typos before an invoice goes out. Invio checks the format and checksum automatically when you add your ABN to your business profile. For a live registration check, use the free ABN Lookup tool.
The 47% no-ABN withholding rule, explained
If a business pays a supplier more than A$75 (excluding GST) for goods or services and that supplier hasn't quoted an ABN, the payer is generally required to withhold tax at the top marginal rate plus the Medicare levy - about 47% - and remit it to the ATO (reported at BAS label W4).
This is a payer-side obligation, not something you do to your own invoices - but it directly affects your cash flow if you invoice without an ABN. A client who is legally required to withhold 47% will simply take it out of the payment, so a supplier who forgets to quote an ABN can lose nearly half of what they billed.
A few exceptions apply: payments under the A$75 threshold, private or domestic supplies (e.g. a one-off job for a household, not a business), and cases where the supplier has provided a signed "Statement by a Supplier" form explaining why no ABN is quoted (for example, the supply is input-taxed or the supplier is not carrying on an enterprise).
The practical takeaway: put your ABN on every invoice, every time - it's the simplest way to make sure you get paid in full and your client stays compliant.
Common ABN Invoicing Mistakes to Avoid
Leaving the ABN off entirely
Your client may be forced to withhold 47% of the payment - put it on every invoice
Mistyping the ABN
Check it is exactly 11 digits and passes the modulus-89 checksum before sending
Assuming an ABN means GST-registered
You can hold an ABN without being GST-registered until you reach A$75,000 turnover
Putting a TFN on a customer invoice
A TFN is a personal/entity tax identifier - only your ABN belongs on an invoice
Burying the ABN in the footer
Keep it in the supplier details block near your business name, where it is easy to find
Missing the buyer ABN on large invoices
For invoices A$1,000+, include the buyer's identity or ABN too
Go FromABN to Invoice
Generate a compliant invoice
Add your ABN once, then it appears on every invoice automatically.
Download a tax invoice template
Use the free tax invoice template AU with an ABN field already in place.
Check GST amounts
Work out the 10% GST before you send the invoice.
Read the full ATO checklist
See every required field, by invoice value.