BAS and Tax Guide for South-East Melbourne Small Businesses

The most common BAS error we see in Bentleigh and Oakleigh is not a miscalculated GST figure. It is a business owner who has written "super" onto a mental list of BAS items, and a December quarter marked in the diary for January.

Neither is right. Superannuation guarantee is never reported on a Business Activity Statement, and the December quarter BAS is not due until the end of February. Both mistakes are easy to make, and both are expensive in different ways: one produces a wrong statement, the other produces a late one.

This guide sets out what a BAS actually reports, how often you have to lodge one, what the 2026-27 dates are, and what it costs when you miss them. Figures are current as at 22 September 2026 and stated for the 2026-27 income year unless noted.

What Does a BAS Actually Report?

The superannuation point matters more than it looks. Super is not an ATO liability in the ordinary case: it is paid to each employee's fund by the quarterly deadline, and the ATO only becomes the payee if you miss it and have to lodge a superannuation guarantee charge statement. Expecting to see super on the BAS leads owners to budget for it in the wrong month, which is how quarterly super deadlines get missed.

What appears on your statement depends on what you are registered for. A sole trader in Carnegie registered for GST with no employees sees GST labels only. A Chadstone retailer with eight staff sees GST plus PAYG withholding. A company paying quarterly tax instalments sees a PAYG instalment label as well.

If your GST turnover is under $10 million you will almost certainly be on Simpler BAS, which reduces the GST section to three labels: G1 total sales, 1A GST on sales and 1B GST on purchases. Businesses at or above $10 million complete the full reporting labels, including export and GST-free sales and capital purchases. The full list of BAS labels is set out in the ATO's business activity statements guidance.

Payroll tax is a separate state obligation and catches growing businesses by surprise. In Victoria the tax-free threshold rose to $1,000,000 a year, or $83,333 a month, from 1 July 2025, and the deduction phases out between $3 million and $5 million of wages, per the State Revenue Office. If you employ contractors, check whether they are caught by the payroll tax contractor provisions before you assume you are under the threshold. Our note on contractor versus employee classification covers the ATO side of the same question.

What Is the Difference Between a BAS and an IAS?

The two forms get used interchangeably in conversation, which causes real problems at lodgement time. A common case: a consultancy in Caulfield turning over $60,000 is not required to register for GST, but it employs a part-time administrator and withholds PAYG. That business lodges an IAS. It has no BAS obligation at all.

The reverse also happens. A GST-registered business with monthly PAYG withholding obligations and quarterly GST can end up lodging monthly IAS forms in the first two months of each quarter and a BAS in the third. Getting the form wrong is not a penalty in itself, but it is usually a symptom of a reporting cycle that has never been checked. We set out the full picture of which form falls due when in our 2026-27 ATO due dates guide, which is the calendar we keep current through the year.

How Often Do You Have to Lodge a BAS?

That last sentence is where a lot of published guidance goes wrong, including an earlier version of this page. Annual GST reporting is not the fallback for a business that is not registered. It is an election available to voluntary registrants: businesses under the $75,000 threshold that chose to register anyway, and would rather deal with GST once a year than four times.

The ATO's power to direct monthly reporting is no longer theoretical. From 1 April 2025 it moved around 3,500 small businesses with a history of non-compliance onto monthly GST reporting, for a minimum of 12 months. Late lodgement, late payment and incorrect reporting are the behaviours that trigger it. In practice this means a business that treats quarterly deadlines loosely can end up with twelve deadlines a year instead of four. The thresholds and the ATO's discretion are set out on its monthly GST reporting page.

When Is Your BAS Due in 2026-27?

A January due date is the single most persistent BAS myth, and it is easy to see why: three of the four quarters fall 28 days after quarter end, so the December quarter looks like it should be due 28 January. It is not. The ATO builds a month of extra time into that quarter to account for the Christmas shutdown.

Source: ATO, Due dates for lodging and paying your BAS, and BAS agent lodgment program 2026-27. The Q4 agent date is marked by the ATO as to be confirmed when the 2027-28 program is developed.

Two concessions are worth knowing. First, lodging your own BAS online gives most businesses an extra two weeks for quarters 1, 3 and 4. It does not apply to quarter 2, because that quarter already carries the one month extension. Second, lodging through a registered agent under the BAS agent lodgment program gives the dates in the right-hand column above. Those concessions are conditional, not automatic: they depend on the agent lodging electronically and on your account being in order.

Where a due date falls on a weekend or public holiday, the ATO's due dates page moves it to the next business day. That is why the 2026-27 December quarter date is 1 March 2027 rather than 28 February. We keep every BAS, IAS, PAYG, FBT, super and TPAR date for the year in one place in our key ATO due dates guide, and update it as the ATO publishes changes. Bookmark that page rather than this one for dates.

Do You Have to Register for GST?

Voluntary registration is a commercial decision, not a formality. It helps when your customers are themselves GST-registered businesses, because they claim the GST back and your price is effectively unchanged to them, while you recover GST on your own costs. It hurts when you sell to consumers, because you either absorb the GST or raise prices by a tenth. A Burwood café registering voluntarily is usually making itself poorer; a Tech or SaaS business selling to Australian companies usually is not.

Turnover is tested on a rolling basis, not at year end. The ATO's registration guidance requires you to register within 21 days of your current or projected GST turnover reaching the threshold. Register late and you can find yourself liable for GST on sales where you never charged it, out of your own margin. For software and digital businesses the place-of-supply rules add another layer, which we cover in our note on GST on app store sales. Ongoing registration monitoring sits inside our small business tax compliance service, and for early-stage companies inside startup accounting and advisory.

What Happens If You Lodge Your BAS Late?

The penalty is per statement, not per quarter of delay, and it applies whether or not you owe tax. Medium entities pay double and large entities five times the base amount. The ATO generally does not apply the penalty where the lodgement produces a refund or a nil result, and it usually warns by phone or in writing before applying it, but neither is a rule you can plan around.

Source: ATO, Failure to lodge on time penalty, and Penalty units (penalty unit $364 from 1 July 2026).

Worked example: a Bentleigh retailer, 70 days late

A GST-registered retailer with net GST payable of $18,400 for the quarter lodges and pays 70 days after the due date. The numbers:

• 70 days is three periods of 28 days or part thereof, so three penalty units: 3 x $364 = $1,092
• GIC on $18,400 at the daily rate of 0.03153425% for 70 days, compounding: $411
• Total cost of being 70 days late: $1,503
• Because GIC is no longer deductible, a base-rate company on 25% must earn $547 of pre-tax profit to fund the $411 of interest alone

That last point is the change most owners have not absorbed. General interest charge and shortfall interest charge incurred on or after 1 July 2025 are not deductible, following the Treasury measure denying deductions for ATO interest charges. Before that date, ATO interest cost you roughly three-quarters of its face value after tax. Now it costs all of it. The rate itself is also high by recent standards: 11.51% for the October to December 2026 quarter, reset quarterly.

What else follows a persistent pattern of late lodgement

• A shift to monthly GST reporting for at least 12 months, as described above.
• Disclosure of the debt to credit reporting bureaus. The ATO can report a business tax debt where you hold an ABN, at least $100,000 is more than 90 days overdue, and you are not effectively engaging with the ATO. A compliant payment plan prevents disclosure, and the ATO gives 28 days written notice first, per its tax debt disclosure guidance.
• Director penalty notices where PAYG withholding and superannuation guarantee amounts remain unreported and unpaid.
• Loss of unclaimed GST credits once the four-year limit expires. See the next section.

If you are already behind, lodge first and negotiate second. A lodged statement with an unpaid balance is a payment problem, and the ATO has payment plans for those. An unlodged statement is a compliance problem, and the options narrow quickly. We cover the remission process and the director penalty timeline in detail in our guide to late BAS lodgement penalties.

Can You Still Claim GST Credits on an Old BAS?

This is the most under-appreciated cost of falling behind, and it is worth being precise about it. The clock does not start when you lodge. It starts from the lodgement due date of the statement in which the credit could first have been claimed, which for an accruals taxpayer is the period the invoice was issued or payment made, whichever came first, and for a cash taxpayer the period the payment was made.

The ATO's time limits on GST credits guidance is explicit that it has no discretion to extend the four years. Two narrow exceptions exist: where the ATO later amends an assessment to treat a supply as taxable that you had treated as input taxed, and where you asked the ATO within the four years to treat a document as a tax invoice. Neither helps the business that simply did not get around to lodging. A capital purchase in a quarter you never lodged is the classic loss: the GST credit on a $60,000 shop fit-out is $5,454 that quietly stops existing.

Should You Lodge Your Own BAS or Use a Registered BAS Agent?

Safe harbour is the part most comparisons leave out, and it is the strongest argument for using an agent. Under the safe harbour provisions, a client is not liable for a failure to lodge on time penalty where they gave the agent all relevant tax information to allow lodgement by the due date, and the delay did not result from the agent's recklessness or intentional disregard of a tax law. The burden of proof sits with you, which is why dated handovers matter. The conditions are set out in the ATO's safe harbour guidance.

When self-lodgement works

Self-lodgement is reasonable where the business is simple: one or two revenue streams, no employees or a single payroll run, a bank feed that reconciles, and no unusual transactions. The online concession gives you two extra weeks in quarters 1, 3 and 4, and you keep the fee. You carry the accuracy risk yourself.

When an agent is the better call

Once you have staff, mixed GST-free and taxable supplies, imported goods, hire purchase or chattel mortgage arrangements, or you are close to a turnover threshold, the coding decisions stop being obvious. In our experience with professional services and trades clients across the south-east, the errors that cost money are not arithmetic. They are GST claimed on wages or bank fees, capital purchases missed at 1B, and GST-free supplies coded as taxable. Anyone you pay to prepare or lodge a BAS must be registered with the Tax Practitioners Board, and you can search its public register free of charge. Check the registration before you engage, not after.

Fees vary widely with complexity and the state of your records. A business with a clean, reconciled ledger costs far less to service than one where the quarter starts with three months of unreconciled transactions, which is why bookkeeping and BAS preparation are usually priced together. Ask for a fixed quarterly or monthly fee rather than an hourly estimate, and confirm in writing whether it includes dealing with the ATO if something goes wrong. Our BAS and IAS lodgement service is quoted on that basis, and our guide to choosing an accountant in south-east Melbourne sets out what else to ask.

How Can Automation Reduce BAS Errors?

Xero, MYOB and QuickBooks Online all handle Simpler BAS and lodge directly to the ATO. The gain is real but narrower than the marketing suggests: software removes transcription errors and gives you a quarter that is already 90% coded. It does not know that your insurance premium includes a stamp duty component with no GST, or that a supplier has stopped being registered.

Three checks catch most of what automation misses. Reconcile the GST control account to the BAS figure before lodging. Review any transaction coded to a GST-free or input-taxed code that is over a set dollar threshold. And run a supplier ABN check annually against the ABN Lookup register. Keep the supporting records for five years from the later of when you prepared them and when the transaction was completed, as the ATO's record keeping rules require. Our bookkeeping guide for Melbourne owners covers how to set the file up so those checks take minutes.

Local BAS and Tax Support Across South-East Melbourne

The obligations are federal, so nothing about a BAS changes between suburbs. What changes is the mix of businesses and the problems they bring. Retail and hospitality concentrations produce GST coding and cash-handling questions. Professional services clusters produce PAYG instalment and personal services income questions. Medical and allied health precincts produce payroll tax and service entity questions.

42 Advisory works with small businesses across the south-east from our Chadstone and Moorabbin offices:

• Chadstone: a retail and business hub serving the broader south-east
• Moorabbin: light industrial, trades and wholesale
• Bentleigh: independent retailers and small professional practices
• Oakleigh: a diverse business community with growing technology and services sectors
• Burwood: hospitality, retail and professional services
• Carnegie: owner-operated retail and services along the Koornang Road strip
• Caulfield: established professional and retail businesses

Sector specialists matter more than proximity once a business gets past a certain complexity. We publish separate guidance for technology and SaaS businesses and for doctors, dentists and health practices, where the BAS is the smallest part of the compliance picture. Victorian medical practices in particular should read our payroll tax guide for medical practices before assuming the payroll tax threshold protects them.

Key Takeaways

• Diarise 1 March 2027, not January. The December 2026 quarter BAS is due 1 March 2027 because 28 February falls on a Sunday. There has never been a January BAS deadline.
• Superannuation is not on the BAS. Budget for it as a separate quarterly payment to employee funds.
• Check which form you should be lodging. No GST registration but PAYG withholding means an IAS, not a BAS.
• Lodge even if you cannot pay. Late lodgement costs $364 per 28 days and can push you onto monthly reporting. Late payment attracts interest that is no longer deductible.
• Do not let old quarters sit. GST credits expire four years after the due date of the statement they belonged in, and the ATO cannot extend that.

Frequently Asked Questions