You are about to issue an invoice, register for GST, onboard a new supplier, or put a new employee on the books, and somewhere in that process someone asks for your Australian Business Number (ABN). If the number is not saved somewhere you can find it, the next step is usually a scramble through old emails, invoices and spreadsheets. The good news is that finding your ABN, or checking an ABN that has been given to you, takes minutes rather than hours once you know where the official record lives.
The process below takes you to a confirmed answer: the 11-digit ABN attached to the entity you trade through, verified against the Australian Business Register (ABR), the official national register of ABNs. One thing readers commonly assume is that a phone call to the ATO, or a question to their accountant, simply produces the number. In practice the reliable place to look is the public register itself, called ABN Lookup, which is free, needs no login, and is open to anyone. What ABN Lookup will not tell you is which of several numbers is the one you should be using today, so the real work is confirming that the number you find belongs to the entity you actually trade through.
Before you start: what you need on hand
Gather these before you search. Most people only need the first two, but the list covers the situations where the process branches:
- The name or names you trade under: your legal name if you are a sole trader, your business name, your company name, or your ACN if you operate through a company. This is the item that trips people up most, because the ABN often sits under a name that is not the one on the shopfront.
- A document that may already show the ABN: an old tax invoice, a business activity statement, a letter from the ATO or the ABR, or your business name registration confirmation all usually carry the number.
- Access to the account you used to register: a myGov account with ATO online services linked, or a login for the ABR portal, if you need to view or change your own record rather than just find the number.
- Your tax file number and identity documents: you will need these if the process ends with you applying for a new ABN, because the Registrar must be satisfied about who you are.
- A clear idea of which entity holds the ABN: the ABN belongs to the individual running the business as a sole trader, to the partnership, to the company, or to the trustee of a trust. If you restructured at some point, the entity that holds the ABN may have changed.
The one decision that shapes the rest of the process is identifying the legal entity that runs the business. ABNs attach to entities, not to trading names, and every check below comes back to that point.
The steps to find your ABN
Search ABN Lookup by name or ACN
ABN Lookup is the public face of the Australian Business Register. You can search it by ABN, by ACN, or by name, and the advanced search lets you filter by state, postcode, tax concessions and deductible gift recipient status. No login is required and there is no fee.
The register itself is established and maintained by the Registrar under s 24 of the A New Tax System (Australian Business Number) Act 1999 (Cth) (the ABN Act), and s 26 of that Act gives the public access to the details held on it. A search result returns the entity name, the ABN, the status, the entity type, the state, whether the entity is registered for GST, and any business names registered to that entity, along with historical trading names where available. Because the register is a public record, s 27 of the ABN Act makes entries admissible in proceedings as prima facie evidence of the matters registered.
Match the listing to the right entity
The ABN belongs to an entity, not to a name. When the search returns a listing, check three fields before relying on it: the entity name, the entity type, and the status.
A common trap is confusing a business name with a legal entity. A business name is registered with ASIC on the Business Names Register and is displayed on the ABN listing for the entity that owns it, but the business name itself has no legal personality. If you trade as "Coastal Kitchens" as a sole trader, the ABN belongs to you, an individual, and the listing will show your name with "Coastal Kitchens" as the business name.
The other common trap follows a restructure. If you started as a sole trader and later incorporated a company, the old ABN belongs to you as an individual and the company holds a different one. The same logic applies when a trust changes trustee or a business is bought and sold. Finding an ABN with a familiar name on it is not the same as finding the ABN you are entitled to use now.
One situation where a search can come up empty even though the person has an ABN: individuals who are sole traders can request non-disclosure of their details in exceptional circumstances, and details stay public until the request is finalised. If you genuinely cannot locate a sole trader's ABN, you may need to ask for it directly.
Check your own documents and online accounts
Before assuming you have lost the number, remember that Australian business documents are required to carry it in several places:
- A tax invoice must let the reader ascertain the supplier's identity and ABN, under s 29-70 of the A New Tax System (Goods and Services Tax) Act 1999 (Cth) (the GST Act). Your own invoices and quotes are the first place to look.
- A pay slip must include the employer's name and the employer's ABN, under regs 3.45 to 3.48 of the Fair Work Regulations 2009 (Cth), made under s 536 of the Fair Work Act 2009 (Cth). This makes pay slips a reliable source when you are tracking down an employer's ABN.
- Letters from the ATO or the ABR confirming your registration, your ASIC business name records, and banking documents for the business account all commonly repeat the number.
If you have an online account, you can also view your registrations through ATO online services, accessed via myGov or the ATO app. For changes, go to the ABR itself: ABN Lookup is read-only, while applying for, updating or cancelling an ABN happens through the Australian Business Register.
Verify the ABN is active and update the details
The status field tells you whether the ABN is current. For most businesses the two statuses you will see are Active and Cancelled. A cancelled ABN should not appear on new invoices, contracts, pay slips or onboarding documents, because it means the registration has been ended.
The Registrar can cancel a registration where the entity was registered under an identity that is not its true identity, was not entitled to an ABN at the time of registration, or is no longer entitled to one, under s 18 of the ABN Act. Cancellation decisions carry notification requirements, and the ABN Act builds in remedies: s 19 allows reinstatement where a registration should not have been cancelled, and s 21 gives the entity rights to object to reviewable ABN decisions under the objection process in the Taxation Administration Act 1953 (Cth).
Keeping the record accurate is an ongoing obligation, not a one-off. The ABR requires you to update your ABN details within 28 days if your circumstances change or the business stops operating, and an ABN can be cancelled if the records show you are no longer carrying on a business. The ABR also conducts entitlement reviews from time to time, where you will be asked to show that your business started, or you took steps to start it, from the date on your application.
If nothing comes up: check your entitlement and apply
An empty search usually means one of three things: you never registered, you searched under the wrong name, or the ABN was cancelled. If you are satisfied you searched correctly and there is no listing, the question becomes whether you are entitled to an ABN at all.
Entitlement is set out in s 8 of the ABN Act. You are entitled if you are carrying on an enterprise in Australia, or if you make supplies connected with the indirect tax zone in the course of carrying on an enterprise. A company registered under the Corporations Act 2001 (Cth) is entitled regardless. Carrying on an enterprise includes running a business, but it is a defined concept with its own boundaries, and it is worth being sure you meet it before you apply, because the ABR warns that people who apply for an ABN, register for GST and claim refunds when they are not entitled can face prosecution.
To apply, you submit the approved form to the Registrar under s 9 of the ABN Act, online through the ABR. The application moves faster when you can be identified from the information provided, such as your tax file number. If the application succeeds you receive the 11-digit ABN immediately and can register for other things, such as GST, straight away. If the Registrar needs to check details you receive a reference number instead, the application is reviewed (the ABR aims for within 20 business days) and you get a letter confirming the ABN within 14 days. A refusal comes with written reasons and options, including review rights, under s 13 of the ABN Act.
If your business is close to the GST registration threshold of $75,000 in GST turnover ($150,000 for non-profits), registering for GST may be the next step. The ATO requires an ABN before GST registration, and once you have one you can register immediately through ATO online services, by phone, or through your tax agent or BAS agent.
Where people get stuck
The patterns that trip people up most are:
- Searching by trading name when the ABN is under the entity name: the listing is found by the legal entity, so search the individual's name, the company name, or the ACN, then check the business names displayed on that listing.
- Finding an ABN that is cancelled or belongs to an old entity: this follows restructures and lapsed registrations. Check the status and entity type before using the number on anything, and do not keep using a cancelled ABN on new documents.
- Assuming a business name is a legal entity: it is not, and contracting, invoicing or hiring in the business name without identifying the entity behind it creates confusion about who is actually liable.
- Expecting every search to return a result: some sole traders have non-disclosed details, and unregistered start-ups have no listing at all, in which case the entitlement question becomes the relevant one.
Finding and verifying an employer's or supplier's ABN
The same register answers the question from the other side, when you need the ABN of the business you are dealing with rather than your own. Search ABN Lookup by the legal name or ACN you have been given, then confirm the entity type and status match who you think you are dealing with.
If you are an employee tracking down your employer's ABN, your pay slips are the primary source, because they are required to state the employer's name and ABN. The entity named in your employment documents should match the entity on the ABN listing, and if it does not, that is worth raising before you accept the paperwork as correct.
If you are onboarding a supplier, the checks that matter are whether the ABN is active, whether the entity is registered for GST (relevant if you need tax invoices to claim input tax credits), and whether the entity type matches the party you are contracting with. Groups that operate multiple companies, and businesses whose trading name resembles other entities, are the cases where a name match alone is not enough. Where you verify ABNs at scale, the ABR's free web services validate ABNs and pre-fill forms rather than relying on manual searches.
The limit of any register check is that it reflects what the entity told the ABR. It confirms the number is active and matches an entity's details; it does not confirm who is actually behind the business day to day. Pair the ABN check with the documents themselves, such as the contract, invoice letterhead and bank details, before you extend credit or pay a deposit.
When to bring in a professional
For straightforward cases, finding an ABN is a do-it-yourself task. Professional help becomes worthwhile when the number is entangled with structure, contracts or tax registrations.
A registered tax agent or accountant can handle the ATO-facing steps: applying for an ABN, responding to entitlement reviews, fixing GST or PAYG registrations, and managing an objection if an ABN decision goes against you. They also see your registrations across the ATO systems, which can reveal why a number is missing or mismatched.
A lawyer's role is different and usually sits alongside. It is to confirm which entity should hold the ABN and to make sure the documents match that entity: employment agreements, contractor agreements, supplier terms and invoices should all name the entity that holds the number, so that rights and liabilities attach where they are supposed to. After a restructure, or where you discover the wrong ABN has been used on contracts or invoices, a lawyer can help you correct the records and manage the risk before a dispute makes it expensive.
The time to get advice early is before you sign a significant contract, after changing your business structure, or if you find registrations on the record that you did not create, which can be a sign of identity misuse.
The entity behind the number
The step that decides whether this process succeeds is matching the number to the legal entity you trade through today, not simply finding an ABN with a familiar name attached. Every document that follows, the invoice, the contract, the pay slip, the business activity statement, should name the same entity that holds the ABN you are using. Skip that match and you will have found an ABN, but not necessarily yours, and the mismatch surfaces later in disputes, payroll problems and GST adjustments, when it is harder to fix.
To summarise the process: search ABN Lookup by name or ACN, confirm the listing shows your entity with an active status, check your own invoices, pay slips and ATO or ABR accounts if the search comes up short, and update your details within 28 days of any change. If there is no listing and you are carrying on an enterprise, apply through the ABR and you will have your 11-digit ABN immediately once your identity is confirmed. If the ABN belongs to a business you are dealing with, verify the entity name, status and GST registration before you rely on it. Where structure, contracts or disputed records are involved, a tax agent and a lawyer are the right next stop.