Which register answers your question? Start here.
If you need to locate an ABN or an ACN, you almost certainly need one website: ABN Lookup. It publishes the public Australian Business Number information held by the Australian Business Register (ABR), it is free to use, and it accepts three kinds of input — an ABN, an ACN, or a name. Because a single search covers all three, the practical question is rarely "which register" and more often "which number do I actually have, and which result should I trust".
The exception is worth knowing. If you are completing a government online form that validates your entity itself, that form may do the lookup for you. The Online Services help article published by the National Environmental Protection Agency describes exactly this pattern: Online Services pre-populates the Entity Name field from the Australian Business Register based on the number you enter. In that setting you are not searching a register at all — you are checking whether a number you already hold is recognised.
What each number identifies
| Number | What it points to | How the public record is searched |
|---|---|---|
| ABN (Australian Business Number) | A business recorded on the Australian Business Register | ABN Lookup, by ABN or name |
| ACN (Australian Company Number) | A registered company, entered as a 9-digit number | ABN Lookup accepts an ACN as a search term; Online Services also validates ACNs against the ABR |
Keep this distinction loose in your own notes until the record confirms it. The two numbers are not interchangeable labels for the same thing, and both are not always present. Not every entity holding an ABN is a company, so "search for the ACN" is not always a meaningful step. When a number fails to resolve, that may mean the format is wrong, the record is not public, the details are out of date, or the entity simply is not registered for that identifier.
Searching ABN Lookup: three entries into the same data
The interface at abr.business.gov.au lets you search for a business by ABN, ACN or name. The three routes behave differently in practice:
- Searching by ABN is the most direct route when you already hold the number — on an invoice, a contract or a supplier form. This confirms the name attached to the number and the details published about it.
- Searching by ACN relies on that ACN being recorded on the Business Register. It is useful when you have been given an ACN and need to confirm the company name that goes with it.
- Searching by name is the entry point when you have no number at all. Work through the candidates returned and match them against other details you hold, rather than assuming the first result is the one you want.
Read results narrowly. A match confirms that an identifier exists and shows what is public about it. It says nothing about whether the entity is trading well, whether it is solvent, or whether the person you are dealing with can bind it.
When the form pre-populates the entity name
Some government systems reduce this to a single field. According to the Online Services help article at onlineservices.environment.gov.au:
- Online Services pre-populates the Entity Name field from the Australian Business Register, so entering a valid number fills the name in for you.
- Entering a 9-digit ACN populates the company name if that ACN exists in the Australian Business Register. That conditional matters — the field populating is itself the confirmation that the number was recognised.
- If you cannot find your ACN through the ACN search, the help article directs you to manually enter an ACN and company name instead. Treat this as a fallback: a manually entered pair is not verified by the pre-population check.
If you hit that wall, go back to a primary source — the company's own registration paperwork, official correspondence issued to it, or a signed document — before submitting anything downstream.
Checklist: your search returns nothing
Work through these in order rather than retrying the same query:
- Re-enter the number without spaces, hyphens or other formatting characters.
- Check the length. An ACN is entered as a 9-digit number, and a mismatch here is a common cause of a failed lookup.
- Search by the other identifier. If the ACN will not resolve, try the ABN, and vice versa.
- Search by name instead, then compare the candidate against the paperwork you hold.
- Confirm whether the entity is actually registered for the identifier you assumed it had.
- Where a form allows manual entry, use it last and record why you did.
If the ABN you are looking for is your own
Finding your own details is only half the job; keeping them accurate is the part with a deadline. Guidance published through the Australian Business Register states that:
- You must update your ABN within 28 days if your details change or your business stops operating.
- Your ABN may be cancelled if records show you are no longer carrying on a business.
- Accurate ABN details help government agencies confirm your identity and check whether you are eligible for grants and emergency support.
The practical consequence is straightforward: an outdated record can cost you access to support you would otherwise qualify for, because eligibility checking depends on what the register holds. Review contact details, business location and operating status whenever something changes, not once a year.
If you need register data at scale rather than one lookup at a time, the ABR also provides "ABN data for your systems" and bulk extract access. That suits validating suppliers or customers in bulk, and it is a separate process from the single-search web tool.
Questions to verify yourself
The register supplies facts. These are the judgement calls left to you:
- Does the name returned match the entity named in your contract, invoice or application?
- Is the record current enough for the decision you are making today?
- If an entity does not appear, is that because it is unregistered, not publicly listed, or because you searched the wrong identifier?
- Where a rule, threshold or eligibility test depends on registration status, which agency administers that rule, and what does that agency's current published guidance say?
Registration details and the interfaces around them change. Confirm current requirements directly with the Australian Business Register at abr.business.gov.au, and where your task sits inside another agency's process, with that agency's own published instructions.
Next steps
- Search ABN Lookup now using the ABN, ACN or name you already have, and record the exact result you get.
- If a government form pre-populates the entity name from your entry, treat the populating field as your confirmation that the number is recognised.
- If your own details have changed in the past month, update your ABN — the register sets a 28-day expectation.
General information only
This article provides general information about public registers. It is not legal, tax, financial or business advice, and it does not assess whether any entity is suitable to deal with. Register records and the tools around them can change without notice. Verify every number, name and deadline against the Australian Business Register or the relevant agency before relying on it, and consult a qualified professional about your specific circumstances.