GST Registration and BAS Cash Flow in Australia: 2026 Guide for Small Business

Crossing the GST threshold is a milestone, but it can create a cash-flow trap. A business that treats every customer receipt as revenue may discover at BAS time that part of the bank balance belongs to the Australian Taxation Office.

The core arithmetic is simple: most taxable sales carry 10% GST, and the GST inside a GST-inclusive price is one-eleventh. The difficult work is deciding when registration starts, which sales count, whether purchases produce credits and when amounts appear on the business activity statement.

Who must register for GST in Australia?

Most enterprises must register when GST turnover reaches or is expected to reach $75,000. The threshold for non-profit organisations is $150,000. Taxi, limousine and ride-sourcing operators generally register regardless of turnover. Australian residents providing taxi travel through an app should not assume a low side-income exempts them.

GST turnover is broadly gross business income, not accounting profit. A consultant billing $90,000 and spending $50,000 has $90,000 turnover, not $40,000. Salary and private investment income are not business turnover merely because the same individual receives them.

Current and projected turnover tests

The ATO uses current GST turnover, generally the current month plus the previous 11 months, and projected GST turnover, generally the current month plus the next 11 months. A one-off disposal of a capital asset can be excluded from projected turnover, as can a sale made solely because the enterprise is ceasing or permanently reducing in size.

Registration is required within 21 days once the business knows it will reach the threshold. Waiting until the end of the financial year can leave the owner liable for GST on past sales even when customers cannot be charged retrospectively.

Which sales are taxable, GST-free or input taxed?

A taxable sale is connected with Australia, made for payment in the course of an enterprise, and neither GST-free nor input taxed. Most professional services, retail goods and commercial transactions are taxable.

GST-free sales can include basic food, many health and education services, eligible exports and certain going concerns. The seller charges no GST but can generally claim credits for GST included in related purchases.

Input-taxed sales commonly include residential rent, most financial supplies and sales of existing residential premises. No GST is charged and related purchase credits are generally unavailable. This distinction is why a residential landlord cannot routinely claim the GST on repairs, while a GST-registered commercial landlord may be able to.

Mixed businesses need allocation

A clinic may make GST-free health supplies and taxable cosmetic supplies. A property group may earn input-taxed residential rent and taxable commercial rent. Expenses used for both require a fair and reasonable apportionment. Keep the methodology and revise it if the use changes.

Pricing before and after registration

If a service previously sold for $1,000 remains advertised at $1,000 GST-inclusive, the business retains only $909.09 before costs and owes $90.91 GST. To preserve $1,000 revenue, it must charge $1,100, subject to contracts and market conditions.

Business-to-business customers registered for GST may focus on the ex-GST cost because they can claim a credit. Consumers cannot claim it and feel the full price. Review quotes, websites, payment links and recurring invoices before the effective registration date.

Australian Consumer Law generally requires consumer prices to display the total minimum price, including GST. Writing “$100 plus GST” in a consumer advertisement may be inadequate where the total can be calculated.

Claiming GST credits correctly

A registered business can generally claim a GST credit where it purchases something for the enterprise, the price includes GST, the supplier is registered, the business pays or is liable to pay, and it holds a tax invoice when required.

There is no credit if the supplier did not charge GST, the purchase is private, the acquisition relates to input-taxed sales, or special rules deny it. Wages, super, bank interest and many government charges do not contain GST.

Motor vehicle example

Jordan buys a vehicle for $66,000 GST-inclusive and expects 70% creditable business use. Ignoring the car limit and other adjustments for illustration, the GST is $6,000 and the initial business-use credit is $4,200. A logbook and odometer evidence should support the percentage. Private use can require an adjustment.

Large cars and luxury vehicles need extra care because the GST car limit can cap the credit. Financing also separates the acquisition from interest and fees; do not code an entire loan repayment as a GST-bearing expense.

Tax invoices

For taxable sales of $82.50 or more including GST, customers generally need a tax invoice to claim a credit. It should identify the supplier, ABN, date, description, price and GST information. Higher-value invoices require buyer identity details. Digital copies are acceptable if readable and retained, generally for five years.

Cash basis versus non-cash basis

Under cash accounting, GST is reported when money is received and credits when suppliers are paid. Businesses with aggregated turnover under $10 million can generally choose this method. Under non-cash or accrual accounting, GST is usually attributed when any payment is made or an invoice is issued, whichever occurs first.

Consider a $22,000 invoice issued on 28 June and paid on 20 August. A quarterly cash-basis business reports the $2,000 GST in the September quarter. A non-cash business may report it in the June quarter, before collecting the cash.

The cash method does not fix poor collections, but it can prevent tax becoming due on long-outstanding debtors. Accrual reporting can suit businesses with strong systems and matched supplier terms.

How often is a BAS lodged?

Businesses with GST turnover below $20 million generally report quarterly unless the ATO requires monthly reporting or the business elects it. Turnover of $20 million or more generally means monthly GST reporting. Eligible voluntary registrants under $75,000 may report annually.

Quarterly periods end 30 September, 31 December, 31 March and 30 June. Standard due dates are commonly 28 October, 28 February, 28 April and 28 July, with possible electronic or tax-agent concessions. Confirm the date shown in Online services for business rather than relying on a generic calendar.

GST is only one BAS obligation

A BAS can also include PAYG withholding, PAYG instalments, fringe benefits tax instalments, wine equalisation tax and fuel tax credits. The net amount therefore may not equal sales GST less purchase GST.

Build a BAS cash reserve

A useful control transfers the GST component of each taxable receipt to a separate savings account. On a $11,000 taxable receipt, transfer $1,000. This deliberately over-reserves because purchase credits will later reduce the liability, creating a buffer for PAYG instalments or seasonal costs.

Suppose quarterly taxable receipts are $132,000 including GST. Sales GST is $12,000. Creditable purchases are $44,000 including $4,000 GST. Net GST is $8,000. If PAYG instalments add $6,500, the BAS payment becomes $14,500.

The $8,000 is not an income-tax deduction. GST collected and credits claimed usually sit outside assessable income and deductions where the entity is registered. PAYG instalments prepay expected income tax and are credited in the annual assessment.

Voluntary registration below $75,000

Registration can benefit a start-up making large taxable purchases or selling mainly to GST-registered businesses. It can also signal commercial scale. But it creates ongoing invoicing, record-keeping, BAS and cancellation obligations, while consumer-facing prices may rise or margins fall.

A start-up buying $33,000 of eligible equipment could potentially recover $3,000 GST. That benefit should be compared with accounting costs and the need to remit GST on future taxable sales. Registration generally must remain for at least 12 months unless the ATO agrees otherwise.

Special traps for contractors and online sellers

Having an ABN does not automatically mean GST registration. Conversely, describing receipts as a hobby does not prevent an activity being an enterprise. Regularity, commercial purpose, scale and businesslike conduct matter.

Marketplace platforms can collect information under Australian reporting regimes. Payment processor totals should be reconciled to accounting records, including fees, refunds and GST. A platform depositing $97 after a $3 fee may still represent a $100 gross sale; recording only the bank deposit understates turnover.

Contractors should also separate GST from personal services income and employee-versus-contractor questions. GST registration does not prove that a worker is legally an independent contractor.

Correcting mistakes and managing debt

Minor errors can often be corrected on a later BAS within ATO time and value limits. Material errors may require revision. Voluntary disclosure before an audit can reduce penalties, but interest may still apply.

If the business cannot pay, lodge on time and contact the ATO about a payment plan. Failure to lodge can add penalties and prevents the ATO from seeing the true debt. Directors should treat GST, PAYG withholding and super obligations seriously because recovery and director penalty rules can create personal exposure in some circumstances.

Monthly close checklist

1. Reconcile every bank and payment processor account.
2. Match sales to invoices, refunds and credit notes.
3. Review suppliers’ GST registration and tax invoices.
4. Separate private and input-taxed expenditure.
5. Reconcile GST control accounts to the draft BAS.
6. Transfer the forecast liability to the reserve account.
7. Review rolling 12-month turnover if not registered.

Choosing systems that scale

Accounting software should apply GST codes consistently, not automatically. Set rules for taxable sales, GST-free income, input-taxed income, capital purchases and expenses without GST. Lock completed periods and attach invoices to transactions.

A bookkeeper can maintain clean records; a registered BAS agent can prepare and lodge permitted obligations; a registered tax agent can advise on broader income-tax consequences. Verify registrations through the Tax Practitioners Board.

GST when selling assets or closing the business

Selling equipment, vehicles, customer lists or commercial premises can create GST even though the sale is unusual. A registered café that sells a coffee machine for $11,000 may have $1,000 GST on the disposal. The amount should not be omitted because the machine appears on the balance sheet rather than the normal sales report.

The sale of a business as a going concern can be GST-free when statutory conditions are satisfied, including that the parties agree in writing and the purchaser is registered or required to register. “GST-free” does not mean informal. Contracts should allocate risk if the ATO later decides the conditions were not met. Property transactions may also involve the margin scheme, withholding at settlement and adjustment events, all of which warrant specialist advice before signing.

Cancellation is not automatic when turnover falls. A business that closes or drops below the threshold can apply to cancel, generally after meeting the required registration period. The final BAS may include increasing adjustments for assets still held where GST credits were previously claimed. Stock, equipment and a vehicle taken for private use can therefore create a final liability even without a cash sale.

Deposits, refunds and bad debts

GST timing for deposits depends on whether the amount is genuine security or part-payment. A refundable security deposit is generally treated differently until it is forfeited or applied. In contrast, a progress payment under a contract can trigger attribution under the normal cash or non-cash rules.

Refunds and price reductions need adjustment notes where required. If a $5,500 taxable sale is refunded in full, the business generally reverses $500 of sales GST in the appropriate BAS period. Accounting software should link the credit note to the original invoice so revenue, debtor and GST accounts all reconcile.

An accrual-basis business that has paid GST on an invoice later written off as bad may be entitled to a decreasing adjustment once the statutory conditions are met. If the debt is later recovered, another adjustment can arise. A cash-basis business normally has not remitted GST on the unpaid amount, illustrating another cash-flow difference between methods.

Annual review of GST settings

At least once a year, compare the GST return to the income-tax return and financial statements. Differences can be legitimate because GST excludes items such as wages and contains balance-sheet transactions, but unexplained gaps deserve investigation. Reconcile total sales, GST-free income, asset disposals, debtor movements and private-use adjustments.

Review whether monthly or quarterly reporting still suits the business. Monthly reporting means twelve lodgments but can deliver refunds sooner for exporters, builders or capital-intensive businesses. Quarterly reporting reduces frequency but allows a larger liability to accumulate. The correct answer depends on transaction volume, systems and discipline, not simply turnover.

Also test supplier master data. An ABN can be cancelled, an entity can stop being registered, and invoices can use the wrong legal entity. ABN Lookup is useful evidence, but the business must still check that the supply and invoice support the credit. Duplicate invoices, personal subscriptions and overseas software charges are frequent coding errors.

Forecasting a growth year

Prepare a 13-week cash-flow forecast with receipts shown GST-inclusive and operating revenue shown ex-GST. Forecast GST credits separately, then place BAS, payroll and super due dates on the cash calendar. A profitable business can fail when rapid growth requires funding debtors, inventory and tax simultaneously.

If monthly taxable sales rise from $8,800 to $22,000, sales GST grows from $800 to $2,000 each month. Over a quarter that is a $3,600 increase before credits. Pricing, deposits and customer terms should change early enough to fund that growth rather than waiting for the BAS reminder.

Get the threshold and timing right

The costly GST mistake is rarely the 10% rate. It is recognising registration too late, pricing contracts incorrectly or spending cash reserved for the ATO. A rolling turnover forecast and monthly reconciliation make the obligation predictable.

Need help registering, selecting a reporting method or cleaning up a BAS? Find Australian accountants and bookkeepers through WealthWorks.