How to Cancel an ABN, Reactivate It or Update Your ABN Details

Short answer: Cancel your ABN through the Australian Business Register once your business has closed, been sold or stopped operating in Australia — online is fastest, using myID — and do it within 28 days of the business stopping. Do not cancel if you are only pausing or still use the ABN for another business. Sort out GST and your final BAS at the same time. If you start trading again with the same structure, you reapply and get the same ABN back; for changed details, update the ABR within 28 days.

The rules below come from the Australian Business Register’s guidance on updating or cancelling your ABN and the ATO’s page on cancelling business registrations, as they stand in the 2026–27 income year. They apply to sole traders, contractors and other ABN holders. If you only need to look up your number first, see how to find your ABN; if you are starting again from scratch, how to apply for an ABN covers the application.

When should I cancel my ABN?

Cancel it when the business has been sold, closed down, or is no longer operating in Australia or making supplies connected with Australia.

Your situation	Cancel the ABN?
You have closed the business for good	Yes, within 28 days
You have sold the business	Yes — the buyer needs its own ABN
You have moved overseas and no longer make supplies connected with Australia	Yes
You are taking a break and plan to restart (seasonal work, parental leave, travel)	No — keep it
You still use the ABN for another business activity	No — keep it, and update the business details
You have taken a job but still run paid side work as a business	Usually no — keep it while the business continues
You are moving from sole trader to a company	The company needs its own ABN; cancel the sole trader ABN once that business stops

The ABR is explicit on both sides of this: it says when you should cancel, and it says not to cancel if you are pausing your business and plan to restart, or still use the ABN for another business. A quiet year is not a reason to cancel. A business that has genuinely ended is.

How do I cancel my ABN?

Cancel it online through the Australian Business Register; the ABR says the fastest way is online using myID.

1. Finish the trading first. Send your last invoices, record the payments you receive and keep the receipts for your final expenses.
2. Set up myID if you have not already, so you can sign in to the ABR’s online services.
3. Cancel the ABN online and give the date the business stopped. The ABR expects you to cancel within 28 days of the business ceasing.
4. Deal with GST and your final BAS — see the next section.
5. Check the result on ABN Lookup. Your record should show the ABN as cancelled from the date you gave.

If a registered tax or BAS agent looks after your affairs, they can cancel it for you; the ABR has a separate page for tax professionals doing exactly that. Other ways to cancel are listed on the ABR’s updating or cancelling page.

What happens to GST and BAS when I cancel my ABN?

When you cancel your ABN, your GST registration is cancelled with it, along with any LCT, WET and fuel tax credits registrations. If you cancel the GST registration on its own when you sell or close, you must do it within 21 days.

• Final BAS. Lodge a BAS for the tax period in which the cancellation takes effect, reporting all sales, purchases and importations in that final period — including the sale of the business or any of its assets. Due dates follow the normal schedule in BAS due dates.
• Assets you keep. If you still hold business assets you claimed GST credits on — tools, a vehicle, equipment — you may have to repay some of those credits as an increasing adjustment on that final BAS. The ATO’s page on adjusting for assets retained after cancelling GST registration works it out as the lesser of the asset’s market value and its GST-inclusive purchase price, multiplied by its business-use share, divided by 11. No adjustment is needed for an asset whose adjustment periods expired before you cancelled — the ATO says, for example, that you usually wouldn’t repay credits on a car held for more than five complete financial years. Claim any GST credits you are still owed on the same BAS.
• Other registrations. PAYG withholding, if you had employees, and any other registrations linked to the ABN also need to be closed; the ATO’s cancelling business registrations page lists them.
• Your tax return. Cancelling the ABN does not end your tax obligations for the year. As a sole trader you still report the business income and expenses up to the closing date in your next return — see the sole trader tax return.
• Records. Keep your invoices, receipts and BAS working papers for 5 years from when you prepared or obtained them, or completed the transaction, whichever is later. Cancelling does not shorten it.

You can also do it the other way round: stay in business, keep the ABN, and cancel only the GST registration if you are eligible — for example, if your turnover has dropped and you registered voluntarily. The same ATO page sets out when that is allowed.

How do I reactivate a cancelled ABN?

You reapply through the Australian Business Register; if your business structure is the same, you are issued the ABN you had before.

For a sole trader, “the same structure” means you are still trading as an individual. You go through the normal application again and, if you are entitled to an ABN, your old number comes back rather than a new one. If the structure has changed — you are now trading through a company, a partnership or a trust — that new entity gets a new ABN.

The entitlement test does not change on reapplication: you need to be carrying on an enterprise, not just planning to one day. Reapply when the work is real, and treat GST as a separate step — register again if your turnover requires it or you choose to. How to apply for an ABN walks through the application.

How do I update my ABN details?

Update them through ABR online services within 28 days of becoming aware of the change.

Change	What to do
New business address or postal address	Update your ABN details online
New phone number or email	Update your ABN details online
Different main business activity	Update the business activity description
New authorised contact	Update the contact details on the record
Changed your name	Update your ABN details so the record shows your current legal name
New or changed registered business name	Deal with the business name itself through ASIC, which holds the business names register

The ABR’s update your ABN details page lists what can be changed online. The 28-day rule matters more than it looks: ABN Lookup is public, and clients use it to check you before they pay — an old address or a stale business activity description makes a legitimate business look doubtful.

What if my ABN was cancelled and I didn’t cancel it?

The Registrar can cancel an ABN when it is satisfied the holder is no longer entitled to one — typically because the records suggest the business is no longer operating.

Check your record on ABN Lookup first; the cancellation date will be shown. If you are still in business, reapply: as a sole trader with the same structure you get the same number back. Until it is reinstated, do not quote the cancelled ABN on invoices — a client who checks it will see it as cancelled and may hold back part of the payment.

After I cancel, where does Keel fit?

Closing a business still leaves work to do: the final BAS, the last tax return and records you have to keep long after the ABN is gone.

Keel: Invoice Maker & Receipts, by Ilura Technology OÜ, is an iPhone app that holds those records — quotes, invoices (as PDFs), receipts and expenses, business mileage and “who owes you”, organised by job and customer. Records stay on the iPhone, with no account, no bank connection and no cloud sync, and the App Store privacy label reads “Data Not Collected”. Keel is free with no invoice limit (free invoices carry a “Made with Keel” footer); the one-time Keel Lifetime purchase ($249.99 USD; the App Store shows your local price) adds accountant-ready exports and advanced reports, plus custom branding, a signature and premium templates.

Keel does not cancel or update ABNs, lodge a BAS, connect to the ABR or ATO, or calculate the tax you owe — those steps stay with you or your agent. Keel on the App Store. For the other Australian guides, see the Australia hub.

Frequently asked questions

How do I cancel my ABN online? Sign in to the Australian Business Register’s online services with myID, which the ABR says is the fastest way, and cancel the ABN with the date your business stopped. Do it within 28 days of ceasing. Then lodge your final BAS if you were registered for GST and confirm on ABN Lookup that the record shows as cancelled.

Does cancelling my ABN cancel my GST registration? Yes. The ATO says that when you cancel your ABN, your GST registration is cancelled too, along with any LCT, WET and fuel tax credits registrations. You then lodge a final BAS for the period in which the cancellation takes effect, reporting all sales and purchases in that period, including any sale of business assets.

Can I reactivate my old ABN? Yes, in effect. You reapply through the Australian Business Register, and if your business structure is the same — for example, you are still a sole trader — you are issued the same ABN you had previously. If you now trade through a company, partnership or trust, that entity receives a new ABN instead.

Should I cancel my ABN if I’m not using it right now? Not if you plan to restart. The ABR says not to cancel your ABN when you are pausing your business and intend to restart later, or when you still use it for another business. Cancel only when the business has closed, been sold or stopped operating in Australia, and then do it within 28 days.

Do I have to cancel my ABN when I become an employee? Only if your business has stopped. Taking a job does not by itself end your business, and many people keep an ABN for occasional side work. If you have genuinely stopped doing any business work, cancel within 28 days of stopping; if you still take paid jobs on your own account, keep the ABN and keep records.

How long do I have to update my ABN details? You must update your details within 28 days of becoming aware of a change, such as a new address, phone number or business activity. The fastest way is through the ABR’s online services. Keeping the record current matters because ABN Lookup is public and clients use it to check who they are paying.

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This article is general information, not tax advice. Consult a qualified Australian tax professional.