You’ve got your first client lined up, so the next job is to get an ABN. The ABN form is free online, yet a single wrong answer or missed deadline can lead to withheld pay, a backdated tax bill, or a second application.
At Australian Business Magazine, we report on the setup slips new businesses make, like a wrong start date or entity type. As an online magazine for founders and sole traders across Australia, we cover registrations and tax rules.
Our guide starts with trading before your Australian Business Number (ABN) arrives, when clients can hold back 47% of your payments. Later sections cover structures, GST timing, and business name checks. By the end, you’ll know how to apply for an ABN and pay each registration fee once.
No ABN Yet? Clients Withhold 47%
Without an ABN on your invoice, any business paying you must send 47% of the payment to the Australian Taxation Office. Not everyone qualifies for an ABN. If the ATO classifies your activity as a hobby rather than a business, your application will be refused.
A trade or other enterprise, though, will face the same withholding. And yes, withholding applies even while your ABN application is pending. The ATO’s guidance says you must quote your ABN before the client pays you, or the deduction goes ahead.
For example, say you bill a client $2,000 for rewiring a Geelong shop. With no ABN on the $2,000 invoice, only $1,060 reaches your account (the other $940 goes to the ATO).
You’ll recover the withheld amount, but only as a credit when you lodge your tax return. Meanwhile, rent and supplier bills come out of the $1,060, so display your ABN on every bill you send.
Your structure also decides which ABN you hold, and switching structures later means new registrations and government fees.
Which Business Structures Cost More to Change Later?
Companies cost more to change than sole-trader setups. Leaving a sole trader structure costs nothing, since you cancel one free ABN. The Australian Securities and Investments Commission (ASIC), by contrast, charges companies a fee to register and another for a name change. Small owners usually register a proprietary limited company, one of several company types, since a public company faces extra reporting rules.
Once the structure is set, two common errors add unexpected costs: needing a new ABN and fixing company registration details.
A Sole Trader ABN Won’t Transfer to an Australian Company Number
Your sole trader ABN belongs to you personally, so a new company needs an Australian Company Number (ACN) first and then a fresh ABN. ASIC treats a company as a separate legal entity with shareholders, a tax file number, and liability for debts.
Once you register the company, ASIC issues the ACN, and you’ll need that number to apply for the company’s new ABN. Remember that the ABN application also asks for your business start date and each director’s personal details upfront.
Before you cancel your sole trader ABN, move any business name across to the company. If you cancel the old ABN first, ASIC will cancel every name attached to the sole trader ABN.
Company Registration Errors and Company Name Changes Both Cost Extra
On the company side, every director needs a director ID before you lodge the registration. If an address or director detail turns out wrong later, you’ll lodge a change-of-details notice with ASIC within 28 days.
ASIC issues a registration certificate as the company joins the company register, and the fee you’ve paid stays non-refundable if you spot an error.
When we compared ASIC’s forms for this guide, a name fix needed two documents, while an address fix needed one notice. You’ll need a special resolution under the Corporations Act, with 75% of the votes cast by eligible members in favour. Form 205 then goes to ASIC within 14 days, with a further fee.
Outside ASIC, you’ll pay for replacement signage, new stationery, and possibly a different web domain (your sign writer won’t repaint the ute for free). Name and structure fixes are one-off costs, while tax registrations come with deadlines.
Late Tax Registrations Leave You Paying GST From Your Own Pocket
A late GST registration leaves you covering tax your customers never paid. When we checked the ATO’s GST rules, a single word deserves a warning: projected.
Your 21-day window starts once current or projected turnover reaches $75,000, even before actual sales get there. If you miss the 21-day window, the ATO will backdate your registration to the point you reached the threshold.
One-eleventh of every sale from the threshold date becomes tax you owe, even though your prices never included GST.
You Need to Register for PAYG Withholding Before Your First Hire
You must register for PAYG withholding before you hold back tax from an employee’s wages. The same PAYG registration applies when you’re the payer and a contractor sends you an invoice with no ABN. As the payer, you’ll send 47% to the ATO, as we covered earlier.
If you register after payday, the ATO will chase the missing amounts plus penalties, since employers carry the legal obligation to withhold.
Since 1 July 2026, Payday Super has also required employers to pay super each payday. Each contribution must reach the fund within seven business days of payday.
A Business Registration Service Can Handle Your Additional Registrations
Want to sort the ABN, GST, PAYG, and business name without four separate forms? The Australian Government’s Business Registration Service lets you apply for the registrations you need in one online application, including company registration.
Alongside the ABN itself, you can tick three additional registrations:
- GST Registration and Credits: If you expect to reach the GST threshold in year one, tick the GST box during your ABN application. You’ll claim GST credits on setup costs like tools and laptops. On sales, you’ll either add 10% to your prices or absorb the GST in your margin.
- PAYG Withholding Registration: Your PAYG withholding registration activates with your ABN confirmation, so you can deduct tax from the opening payslip. You’ll report the withheld tax on your activity statement, alongside any GST you collect.
- Business Name Registration: ASIC registers your trading name for a one-year or three-year fee. The ABN itself stays free through the Australian Business Register, so a sole trader pays only for the name.
Registered tax agents and private services can lodge your business registrations for you, but agents charge for the lodgement. If you’re a sole trader with no staff, the government form will cover your ABN, GST, and business name without an agent.
Before ASIC registers your business name, your ABN details need to match the name you plan to use.
Registering a Business Name? Check Your ABN Details Match First
Every registered business name sits on an active ABN, and ASIC rejects any name application without an ABN attached (ASIC’s name register costs nothing to search before you secure a name).
A client may spot a mismatch between the name you operate under and your ABN record before you do. Say the client’s accounts team looks up your ABN and finds only “J. Nguyen”, with no sign of “Coastline Plumbing“.
ABN Lookup stopped displaying unregistered trading names on 31 October 2025. Until you register “Coastline Plumbing“, the client can hold your invoice while staff confirm your identity.
A side-by-side comparison of three records catches the common mismatches before you lodge:
| Record | What Goes Wrong | How to Fix It |
| Registered business name | The name still sits on your old sole trader ABN after you switch to a company. | Request a transfer number through ASIC Connect, then apply for the name under the company’s ABN. |
| Business address | ASIC and the ABR show different addresses after a move. | Update the address with ASIC and the ABR within 28 days. |
| Owner details | A partner leaves, and the old partnership’s ABN no longer fits the remaining owners. | Apply for a new ABN, then follow the row 1 transfer steps. |
When all three records match, payables staff can verify your business identity on ABN Lookup in one search. Clients then have no reason to hold your payment. A recheck whenever you move premises or change partners will catch new mismatches inside the 28-day window.
Each row takes minutes to check before you trade, while a fix after launch can stall a payment.
Get Your ABN Right Before You Send Your First Invoice
Nearly every cost in this guide traces back to setup choices, with late GST and PAYG registrations as the later costs. Three steps keep setup costs down before you trade: choose your structure, get your ABN with any business name, and check whether GST applies.
PAYG withholding then joins your tax registrations before your first hire. With your structure, ABN, and GST settled first, you’ll avoid the 47% deduction and a second round of ASIC fees.
Your turnover still needs a monthly check, since the GST threshold can arrive mid-year. For your next move, Australian Business Magazine’s guides on tax and business structures walk you through each step of the registration process.
