The honest answer is: it depends on exactly which address you mean, because "ABN registration" and "ASIC registration" actually involve several different address fields, and the PO Box rule is not the same across all of them. Here is where a PO Box works, and where it does not.
ABN registration
Your ABN application asks for your business contact details, including an address, and a separate postal address for correspondence [Salt Space, saltspace.com.au].
Your principal place of business, the main address recorded against your ABN, must be a street address in Australia, not a PO Box [business.gov.au].
However, businesses commonly use a PO Box or virtual office service for their separate postal address specifically, particularly if they run the business from home and would rather not give out that address for general correspondence [business.gov.au].
In short: the core ABN address needs to be a real street address. The postal address attached to it can be a PO Box.
ASIC company registration: registered office
This is the one with no flexibility at all.
ASIC requires a real, physical street address for your registered office, and will reject any application that lists a PO Box for this purpose [Lawpath, lawpath.com.au].
This applies regardless of company size, structure, or how little mail the company expects to receive.
ASIC company registration: principal place of business
Same rule.
ASIC requires a street address for both the registered office and principal place of business, and a PO Box alone does not meet the requirement for either [Sprintlaw, sprintlaw.com.au].
Business name registration: the one place a PO Box actually works
This is the genuine exception.
When you register a business name with ASIC, the contact address ASIC uses to send official notices and letters can be a physical street address or a PO Box in Australia [ASIC, asic.gov.au].
This is a separate register from the companies register, and the rules are different specifically because a business name registration does not carry the same registered office requirement that a company does.
Why the distinction trips people up
People often use "register my business" loosely to mean any combination of getting an ABN, registering a company, and registering a business name, when these are actually three separate processes with three separate sets of address rules.
The PO Box question genuinely has different answers depending on which one you are doing.
If you want privacy without a PO Box
For your company's registered office or principal place of business, where a PO Box is not an option, a virtual address service gives you a real street address that keeps your home address off the public record, while satisfying the physical street address requirement that a PO Box cannot meet.
Space Penguin offers virtual addresses in Sydney and Melbourne from $20 per month plus GST, with no setup fee and no lock-in. The address is eligible for ASIC registration and ABN purposes. Visit spacepenguin.io/virtual-address for current details.
FAQs
Can I use a PO Box for my company's registered office?
No. ASIC requires a physical street address and will reject any application listing a PO Box for this purpose.
Can I use a PO Box for my business name registration?
Yes, for the contact address ASIC uses to send notices. This is a separate register from companies and has different address rules.
Can I use a PO Box for my ABN's postal address?
Yes, for the separate postal address attached to your ABN, even though your principal place of business itself must be a real street address.
Why does ASIC require a street address for registered offices but not for business name notices?
These are governed by different parts of the regulatory framework with different purposes. A registered office is where legal documents are formally served, which requires a genuine, accessible location. A business name notice address is more administrative in nature.
If I am a sole trader, do any of the stricter registered office rules apply to me?
No. The registered office requirement under the Corporations Act applies only to companies. Sole traders are governed by the ABN and business name rules described above.