BAS Explained: What Small Business Owners Need to Know

BAS stands for Business Activity Statement. A BAS is the form Australian businesses use to report and pay obligations such as GST, PAYG withholding and PAYG instalments to the ATO on a regular cycle. Most businesses lodge quarterly, though some lodge monthly or annually depending on turnover and registration choices. If you’re registered for GST or withhold tax from employee wages, you’ll generally have an activity statement obligation.

This article explains what a BAS is, how it works, what’s reported and when small businesses need to lodge one.

This article contains general information only and isn’t personal tax advice. Every business is different, so speak with a registered BAS agent or accountant about your specific situation.

Key takeaways:

• A BAS commonly reports GST, PAYG withholding and PAYG instalments — three separate obligations combined onto one form.
• Most businesses lodge quarterly, due on the 28th day of the month after the quarter ends (except quarter 2, due 28 February) — turnover above $20 million generally means monthly lodgement instead.
• You generally need to register for GST once your turnover reaches $75,000 ($150,000 for non-profits), and registration needs to happen within 21 days of reaching that threshold.
• A BAS still needs to be lodged even with nothing to report — a nil BAS avoids a failure to lodge penalty that a missed lodgement can trigger.
• BAS preparation depends on current, reconciled bookkeeping — an accurate BAS can’t be built from unreconciled or incomplete records.
• A BAS and a tax return are different things: a BAS reports GST and PAYG on a recurring cycle through the year; a tax return reports total income and deductions annually.

What is a BAS?

A Business Activity Statement is a form the ATO issues to businesses with certain reporting obligations, including businesses registered for GST. It allows several tax obligations to be reported and paid through a recurring statement rather than through separate lodgements.

The specific obligations reported depend on what the business is registered for. For example, a GST-registered sole trader with no employees reports different things from a company with staff and PAYG withholding obligations, even though both may use the BAS.

What’s actually reported on a BAS

For most small businesses, a BAS covers three things: GST (the difference between GST collected on sales and GST credits claimed on purchases), PAYG withholding (tax withheld from employee wages and forwarded to the ATO), and PAYG instalments (prepayments toward the business or individual’s expected annual income tax bill). Less commonly, a BAS can also include fringe benefits tax (FBT) instalments, luxury car tax, or wine equalisation tax, depending on the nature of the business — these apply to a smaller subset of businesses and aren’t part of a typical small business BAS.

Who actually needs to lodge one

Broadly, if you’re registered for GST, you have a BAS obligation. If you’re not GST-registered but you withhold tax from employee wages (PAYG withholding), you’ll usually still have activity statement obligations for that withholding. A business below the GST registration threshold with no employees generally has no BAS obligation at all, unless it’s chosen to register for GST voluntarily — which some businesses do to claim GST credits on purchases even before they’re required to.

How often you lodge, and when it’s due

Lodgement frequency is generally tied to GST turnover: quarterly if turnover is under $20 million (unless the ATO directs otherwise), or monthly if turnover is $20 million or more, or if the business chooses to report monthly regardless of turnover. Quarterly activity statements are due on the 28th day of the month following the quarter, except quarter 2 (October–December), which is due 28 February the following year. Monthly activity statements are due on the 21st of the following month. Businesses that lodge and pay online may also qualify for an extra two weeks on quarters 1, 3 and 4.

The GST component, explained

GST-registered businesses generally charge GST on their sales and can claim GST credits for the GST included in the price of things they buy for the business. The BAS reports the net position — GST collected minus GST credits claimed — as either an amount payable to the ATO or a refund owing to the business. Not every sale attracts GST; some, like most financial supplies and residential rent, are input-taxed and don’t generate GST credits either. We’ve covered GST itself — the rate, credits and registration threshold — in more depth in our GST explained guide.

To see how the net position actually works: a Melbourne café that collects $9,000 in GST on sales during the quarter, and can claim $3,200 in GST credits on stock, rent and other GST-inclusive purchases, would report a net GST liability of $5,800 for that period — separate from whatever PAYG withholding or instalment amount is also due on the same BAS.

What is Simpler BAS?

Simpler BAS is the GST reporting method used by many small businesses. Under Simpler BAS, businesses generally report total sales, GST on sales and GST on purchases, rather than completing some of the additional GST labels required under full reporting.

Simpler BAS changes the GST information reported on the statement; it doesn’t mean the business no longer has to report other applicable obligations, such as PAYG withholding or PAYG instalments.

The PAYG withholding component, explained

If the business has employees, PAYG withholding is the tax withheld from each employee’s pay and forwarded to the ATO on their behalf, based on the amounts calculated through payroll each pay run. It also applies to certain payments to contractors who don’t quote an ABN. The total withheld across the BAS period is reported and remitted through the BAS, separate from the GST figures on the same form.

The PAYG instalments component, explained

PAYG instalments are a different thing entirely, despite the similar name — they’re prepayments toward the business or individual’s own expected income tax bill for the year, based on prior income or a rate set by the ATO, rather than tax withheld from someone else.

One common source of confusion is treating PAYG withholding and PAYG instalments as the same obligation because they appear on the same statement — withholding is about employees’ tax; instalments are about the business’s own eventual tax bill, credited against the final assessment once the annual tax return is lodged.

Why your bookkeeping has to be current before you can prepare a BAS

A BAS can only be as accurate as the transaction records behind it. GST needs to be coded correctly on every sale and purchase, PAYG withholding figures need to match what payroll actually calculated and paid, and any input-taxed or GST-free transactions need to be identified correctly rather than defaulted to a standard GST code.

This is why BAS preparation and bookkeeping are so closely linked — an accountant or BAS agent working from unreconciled records has to fix the underlying bookkeeping before an accurate BAS can even be attempted, which is a large part of why catching up overdue bookkeeping usually needs to happen before overdue BAS periods can be lodged accurately.

One issue we regularly see is a business assuming its accounting software automatically fixes GST coding mistakes. It doesn’t — if a transaction is coded incorrectly at the time it’s entered, the BAS built from it will usually be wrong too, no matter how clean the software’s reports look on the surface.

How does BAS work?

A BAS works by bringing the tax obligations your business needs to report for a particular period into one activity statement. Before lodging, you reconcile the relevant transactions, check GST and payroll figures, calculate the amounts to report, review them against your records, and then lodge the statement and pay any amount owing.

The exact process depends on which obligations apply to your business:

Common BAS mistakes small businesses make

• Coding a transaction with the wrong GST treatment — treating a GST-free or input-taxed transaction as a standard-rated one, or vice versa.
• Claiming GST credits without a valid tax invoice on hand to support the claim.
• Missing the difference between cash and accrual GST reporting, which changes which period a transaction should be reported in.
• Confusing PAYG withholding with PAYG instalments when reviewing the figures before lodgement.
• Leaving reconciliation until just before the due date, which leaves little time to investigate a discrepancy properly.

Who can actually lodge a BAS for you

A business can prepare and lodge its own BAS directly. Many choose to use a bookkeeper, BAS agent or accountant instead, particularly once transaction volume, payroll or GST treatment gets more complex. Anyone preparing or lodging a BAS for a fee on someone else’s behalf generally needs to be registered as a BAS agent or tax agent under the Tax Agent Services Act — our bookkeeper vs accountant guide covers where BAS agent registration fits alongside those two roles specifically.

What happens if you fall behind

Missing a BAS due date generally means potential failure to lodge penalties and general interest charge on any amount owing, and it gets harder to reconstruct accurate figures the longer a period goes unreconciled. If you’re currently behind, our guides on what happens when you miss a BAS deadline and getting caught up on overdue BAS lodgements cover the practical next steps in more depth than this explainer does.

Quick recap: what’s on a typical small business BAS

• GST collected on sales, less GST credits claimed on purchases
• PAYG withholding from employee wages (if you have staff)
• PAYG instalments toward your own expected income tax
• Reported quarterly for most small businesses, due the 28th of the month after the quarter (28 February for quarter 2)
• Lodged even when there’s nothing to report, as a nil BAS

Getting help

If BAS preparation is taking longer than it should, or you’re not confident the GST treatment on your transactions is correct, our BAS services page covers how we handle BAS preparation and lodgement for Melbourne small businesses under fixed monthly pricing. If your books need reconciling before your next BAS is due, our bookkeeping services page covers that side of the work.

Official resources

• Business activity statements (BAS) — ATO
• Due dates for lodging and paying your BAS — ATO
• Registering for GST — ATO
• Claiming GST credits — ATO
• Input-taxed sales — ATO
• BAS services — Tax Practitioners Board