ABN vs ACN — What to Include on Your Australian Invoice
ABN identifies your business for tax. ACN identifies your company registration. Use the right one to avoid payment delays.
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Why it matters
Clients may reject invoices missing the right identifiers. Knowing when to show ABN and ACN avoids delays and helps accounts teams match records quickly.
Example: Sam runs a small Pty Ltd and forgot to include the ACN; the client held payment until a corrected invoice arrived.
ABN vs ACN comparison
| Field | ABN | ACN |
|---|---|---|
| Purpose | Tax/business identifier | Company registration number |
| Length | 11 digits | 9 digits |
| Who needs it | Businesses and sole traders | Companies (Pty Ltd) |
| Where it appears | Near business name/address | Next to ABN under business details |
How it works with QuickInvoice
- Add ABN (11 digits) and, if you are a company, ACN (9 digits). Inline checks help format correctly.
- Add client and items; toggle GST only if you charge it.
- Download a tidy A4 PDF with identifiers shown under business details.
Common mistakes
- Showing an ACN when you are a sole trader (not required).
- Leaving off ABN completely when issuing tax invoices.
- Using spaces or non-numeric characters in ABN/ACN (use digits only).
FAQ
Do sole traders need an ACN?
No. Sole traders typically only have an ABN.
Where should ABN/ACN appear?
Near your business name and address at the top of the invoice.
Do I need both ABN and ACN?
If you are a company, yes — include both for smoother processing.
Will QuickInvoice validate lengths?
Yes — ABN (11 digits) and ACN (9 digits) with gentle inline warnings.