GST is one of those things that sounds simple enough on the surface. You collect GST on sales, claim GST on eligible purchases, lodge your BAS, and move on. In practice though, it’s rarely that neat.
For a lot of small business owners, GST becomes one of the first real signs that the business has moved from “getting started” to “properly operating”. There are more rules to follow, more deadlines to manage, and more room for small errors to turn into bigger problems later.
The good news is that most GST mistakes small business owners make are preventable. They usually come down to timing, record keeping, misunderstanding what can be claimed, or simply not having the right systems in place as the business grows. So with that in mind, here are some of the most common GST mistakes we see small businesses make in Australia, and what to watch out for.
One of the most common GST mistakes for small business owners is missing the point where GST registration becomes compulsory.
In Australia, most businesses need to register for GST once their GST turnover reaches $75,000 or more (for not-for-profit organisations, the threshold is generally $150,000). This is based on turnover, not profit, which is where some business owners get caught out. For example, a business might be bringing in more than $75,000 in sales but only making a modest profit after expenses. That doesn’t necessarily mean GST can be ignored; if the GST turnover threshold has been reached, registration may be required.
It’s also important to keep an eye on projected turnover, not just what’s already happened. A strong few months, a new contract, or a sudden increase in sales can push a business over the threshold sooner than expected.
Some new business owners assume they can add GST to their invoices because they plan to register soon, or because they think it makes the business look more established. This is a problem.
Generally, if a business isn’t registered for GST, it shouldn’t be charging GST on its sales. Doing so can create confusion for customers, problems with invoicing, and potential issues when it comes time to report to the ATO. It’s worth getting this right from the start. If GST registration is coming up soon, it’s better to plan the timing properly rather than guessing.
The opposite mistake is also common; a business registers for GST, but its invoices, pricing, website, quoting templates or accounting software aren’t updated properly. This can leave the business absorbing the GST out of its own margin.
For example, if you quote a customer $1100 and forget to account for GST, that amount may include $100 of GST that needs to be reported. Unless your pricing was designed with GST in mind, your profit on the job may be lower than expected.
When a business registers for GST, it’s worth reviewing:
- Invoice templates
- Online checkout settings
- Proposal and quoting documents
- Point-of-sale systems
- Website pricing
- Accounting software tax codes
- Recurring invoices
- Contracts and service agreements
A small setup issue can quietly affect every sale that follows.
A lot of businesses are keen to claim GST credits on their expenses, and rightly so (GST credits can make a meaningful difference to cash flow). However, you generally need proper records to support those claims. For purchases over $82.50 including GST, a valid tax invoice is usually required.
This is where things can get messy. A bank transaction, EFTPOS receipt or order confirmation may not always be enough. If the document doesn’t show the right details, including the supplier’s ABN and the GST amount where required, the claim may not stand up if reviewed.
A good rule of thumb is to collect the tax invoice at the time of purchase, not three months later when the BAS is due. Chasing missing invoices after the fact is frustrating, time-consuming, and easy to put in the too-hard basket.
Not every business expense includes GST. Some expenses are GST-free, input-taxed or simply outside the GST system. Common examples may include certain bank fees, some government charges, wages, residential rent, and purchases from suppliers that aren’t registered for GST.
This is one of the more common GST mistakes small business owners make when coding transactions in their accounting software. They see an expense and assume GST can be claimed, but that’s not always the case.
The issue often isn’t one large mistake; it’s lots of small incorrect claims that add up over time. Accounting software can help, but only if the GST codes are set up and used correctly. The software won’t always know whether GST applies unless the transaction has been coded properly.
Cloud accounting software is a fantastic tool, but it’s not a substitute for knowing what the numbers mean. One of the traps we often see is business owners relying too heavily on default GST codes. A recurring transaction may be coded incorrectly once, and then the same mistake repeats every month. Supplier rules can also be set up incorrectly, meaning future bills are treated the wrong way automatically.
Common coding issues include:
- Treating GST-free purchases as taxable purchases
- Claiming GST on wages or superannuation
- Applying GST to bank transfers between accounts
- Coding loan repayments incorrectly
- Treating asset purchases as ordinary expenses
- Claiming GST on the full amount of mixed-use expenses
These mistakes can flow straight through to the BAS, and then by the time they’re noticed, several reporting periods may need to be reviewed.
Small business owners often move quickly. A personal card gets used for a business purchase. A business card gets used for a personal expense. Money moves between accounts without a clear note. Before long, the bookkeeping becomes harder than it needs to be.
From a GST perspective, this creates two main problems.
- First, GST may be claimed on expenses that aren’t actually business-related.
- Second, legitimate business expenses may be missed because the records are scattered across personal and business accounts.
Keeping business and personal spending separate is one of the simplest ways to reduce GST errors. It also makes life much easier when preparing BAS, tax returns, cash flow reports and business performance reviews.
Motor vehicle expenses are another area where small businesses can run into trouble. The GST treatment can depend on how the vehicle is used, how it’s financed, whether there’s private use, whether the business is registered for GST, and whether the correct records are kept.
A common mistake is claiming GST on 100% of vehicle expenses when the vehicle is partly used for private purposes. Another is not correctly treating the purchase of a vehicle, particularly where finance is involved.
Cars, utes, equipment and business vehicles can all have different considerations; it’s worth getting advice before making a major purchase, rather than trying to unwind the GST treatment later.
Small businesses may have a choice between reporting GST on a cash basis or a non-cash basis, depending on their circumstances… this difference matters.
On a cash basis, GST is generally reported when payment is received or made. On a non-cash basis, GST is generally reported when an invoice is issued or received, even if the money hasn’t changed hands yet. Confusing the two can lead to GST being reported in the wrong BAS period, and this can affect cash flow, create unnecessary stress, and make the accounts harder to reconcile.
This is especially important for businesses with long payment terms, large invoices, slow-paying customers or project-based work. The right method can make a real difference to how manageable GST feels throughout the year.
BAS deadlines have a habit of coming around quickly. When bookkeeping is left until the last minute, GST mistakes become much more likely. Transactions are rushed. Receipts are missing. Bank feeds are unreconciled. Questions get guessed instead of checked.
Late lodgement can also create unnecessary penalties, interest and pressure on cash flow. The best BAS process isn’t a heroic effort every quarter; it’s a steady routine. When accounts are kept up to date during the month, BAS preparation becomes far less painful. A clean process might include:
- Reconciling bank accounts regularly
- Saving tax invoices as you go
- Reviewing GST coding before lodgement
- Checking debtors and creditors
- Setting aside GST collected from customers
- Reviewing unusual or large transactions
- Asking questions before lodging, not after
GST collected on sales isn’t really business income… it’s money collected on behalf of the tax system. That can be easy to forget when cash is sitting in the business bank account. The business may use it to pay wages, suppliers, rent or other operating costs, only to find there’s not enough left when the BAS payment is due.
This is one of the most common GST mistakes small business owners make, particularly in growing businesses where cash flow is already tight. A separate GST or tax savings account can help. Even if the amount transferred is only an estimate, it creates a useful buffer and reduces the shock when BAS time arrives.
Not every sale has the same GST treatment. Some goods and services are taxable. Some may be GST-free. Some may be input-taxed. Some transactions may involve exports, deposits, reimbursements, grants, property, financial supplies or other special rules.
For many small businesses, most sales will be straightforward… but when something unusual happens, it’s worth pausing before applying the standard GST treatment. Examples that may need closer attention include:
- Selling overseas
- Receiving grants or rebates
- Charging deposits
- On-charging costs to clients
- Selling business assets
- Dealing with residential property
- Offering mixed packages of goods or services
- Working across different industries or states
The mistake isn’t always getting the answer wrong; sometimes the mistake is assuming there’s nothing to check.
Good GST reporting relies on good records. That doesn’t mean keeping a shoebox full of receipts and hoping for the best; it means having a reliable system for capturing, storing and reviewing the documents that support the numbers in your BAS. Poor record keeping can lead to missed GST credits, incorrect claims, duplicated expenses, unreconciled transactions and stressful ATO reviews.
A good record-keeping system should make it easy to answer simple questions:
- What was this transaction for?
- Was it business-related?
- Was GST included?
- Is there a valid tax invoice?
- Has it already been claimed?
- Which BAS period does it belong to?
If those questions are hard to answer, the system probably needs attention.
It’s tempting to treat BAS lodgement as an admin task… open the software, check the figures, lodge the form, move on. But a quick review can catch a lot of issues. Before lodging, it’s worth looking for anything that seems unusual. Has GST collected changed significantly from last quarter? Are expenses higher than expected? Are there large transactions that need checking? Do the figures make sense compared to what happened in the business?
GST reporting isn’t just compliance; it’s also a chance to understand what’s happening in the business. A BAS review can highlight cash flow pressure, pricing issues, unexpected cost increases, or changes in sales activity.
Most GST issues start small. A coding question. A missing invoice. A new type of sale. A supplier that doesn’t charge GST. A BAS that doesn’t look quite right. The trouble starts when these questions are left unresolved for months or years. By the time the business asks for help, the issue may have affected multiple BAS periods. Fixing it then becomes more involved than it needed to be.
Getting advice early is almost always easier. It gives the business a chance to correct the process, not just the mistake.
Most GST mistakes small business owners make are avoidable with the right habits and support. A few practical steps can make a big difference:
- Register for GST at the right time
- Keep personal and business spending separate
- Use accounting software properly
- Check GST codes regularly
- Keep valid tax invoices
- Reconcile accounts often
- Understand whether you report on a cash or non-cash basis
- Put GST money aside
- Review BAS before lodging
- Ask for advice when something changes
GST doesn’t need to be overwhelming, but it does need to be managed properly. As a business grows, the systems that worked in the early days often need to grow with it.
At Elevated Accounting, we work closely with small business owners who want their accounting to feel clearer, more manageable and more useful. Whether you need help registering for GST, preparing and lodging BAS, cleaning up your bookkeeping, reviewing your accounting software, or understanding where your business stands, our team can help you get on top of the details.
We’re here to make the numbers easier to understand, help you avoid costly mistakes, and give you the support you need as your business grows. If GST has started to feel harder than it should, or you simply want confidence that everything’s being handled properly, get in touch with Elevated Accounting for a free initial consultation.
