Yes. You can run as many businesses or ventures as you like under a single ABN, provided every business operates under the same legal structure. The ABN is tied to the entity, meaning you, a company, a partnership, or a trust, not to a specific business idea or trading name.
Why this works the way it does
Your ABN identifies the legal entity carrying on the business, not the brand or activity itself [Sprintlaw, sprintlaw.com.au].
If you are a sole trader, that entity is you personally. You can run a graphic design business and a separate side venture selling handmade goods under that same ABN, since both are simply you, the individual, conducting different activities.
The same logic applies to a company. A Pty Ltd company has one ABN, and that company can run multiple business lines or brands under it, each with its own registered business name, while remaining one legal entity, one tax return, and one ASIC annual review fee [Lawpath, lawpath.com.au].
When you actually need a separate ABN
You need a new ABN only when the legal structure itself changes, not when you simply add a new venture.
If you are a sole trader and decide to incorporate a company for a new business, that company is a separate legal entity and needs its own ABN, even though you personally already have one as a sole trader [LegalVision, legalvision.com.au].
A sole trader cannot hold two sole trader ABNs at the same time. If you have somehow ended up with more than one, contact the Australian Business Register to cancel the extra one [Sprintlaw, sprintlaw.com.au].
Registering separate trading names under the same ABN
If you want to operate each business under its own name rather than your own legal name, you register each as a business name through ASIC Connect, linking every name back to the same ABN.
There is no limit on how many business names you can register against one ABN.
Registration costs $45 for one year or $105 for three years per name [ASIC, asic.gov.au].
What stays combined regardless of how many businesses you run
Tax
All income earned under your ABN is reported on a single tax return for that entity, regardless of how many trading names sit underneath it [upcover, upcover.com].
GST registration
The $75,000 GST registration threshold applies to your combined turnover across every business under the ABN, not to each one individually. If your total income across all ventures passes $75,000, you must register for GST, even if no single business on its own reaches that figure [upcover, upcover.com].
Liability
This is the part most worth thinking carefully about.
Running multiple businesses under one ABN and one legal entity means their risks are not separated. A legal claim or debt against one business can affect the assets of the others sitting under the same ABN [LegalVision, legalvision.com.au].
If you want genuine risk separation between ventures, particularly if one carries materially higher risk than the others, a separate legal entity and ABN for that venture is worth considering.
What this means for your business address
If you run several brands under one ABN, you can use the same registered address across all of them, since they share the same underlying legal entity.
Many people in this situation still choose to present a distinct, professional address consistently across each brand's invoices and website, separate from a home address, even though only one ABN sits behind everything.
Space Penguin offers virtual addresses in Sydney and Melbourne from $20 per month plus GST, suitable for ABN registration and consistent use across multiple trading names under the same entity. Visit spacepenguin.io/virtual-address for current details.
FAQs
Do I need a new ABN for every business name I register?
No. You register each business name separately through ASIC, but all of them link back to your single existing ABN, provided they share the same legal structure.
Can a sole trader and a company share the same ABN?
No. They are different legal entities. A sole trader's personal ABN and a company's ABN are entirely separate, even if the same person is behind both.
Does running multiple businesses under one ABN protect each business from the others' debts?
No. Since they share the same legal entity, a claim against one business can affect the assets of the others under that same ABN. Separate entities are required for genuine liability separation.
How much does it cost to register an additional business name?
$45 for one year or $105 for three years through ASIC, per business name [ASIC, asic.gov.au].
Do I need to register for GST separately for each business?
No. GST registration is based on your combined turnover across every business under the ABN. If the combined total exceeds $75,000, you register once, covering all of them.