What Is a Business Activity Statement (BAS)? - 2025-26 Guide

A Business Activity Statement (BAS) is the form Australian businesses registered for GST use to report and pay tax obligations to the ATO. For most small businesses, this means a quarterly form lodged four times per year covering GST collected on sales, GST credits claimed on purchases, and PAYG withholding deducted from employee wages.

This guide covers everything: what a BAS is, who needs to lodge one, how to read the labels, how to calculate the amounts, when each quarter is due, how to lodge it, and what the penalties are for late lodgment. For the due dates already confirmed from the ATO’s official schedule, the 2025-26 quarterly deadlines are 28 October, 28 February, 28 April, and 28 July. For professional BAS lodgment, see our registered BAS agent services in Adelaide.

What Is a BAS Statement?

BAS stands for Business Activity Statement. It is a tax reporting form submitted to the Australian Taxation Office (ATO) that covers several different tax obligations in a single lodgment. The primary purpose of the BAS is to report the Goods and Services Tax (GST) your business has collected on sales and the GST credits you can claim on business purchases.

Beyond GST, the BAS also serves as the form for reporting and paying:

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  PAYG withholding: the income tax you have withheld from employees’ wages and must remit to the ATO
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  PAYG instalments: prepayments of your own income tax liability if the ATO has assessed you for this obligation
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  Fringe Benefits Tax (FBT) instalments: if your FBT liability exceeded $3,000 in the previous year
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  Wine Equalisation Tax (WET): if you are a wine producer, distributor, or importer
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  Luxury Car Tax (LCT): if you sell or import luxury vehicles above the LCT threshold
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  Fuel Tax Credits (FTC): if your business uses fuel in heavy vehicles, plant equipment, or machinery

For most small businesses, the BAS primarily covers GST and PAYG withholding - the other taxes apply only to specific industries. The ATO provides a complete explanation on the ATO’s Business Activity Statements page.

Who Needs to Lodge a BAS?

You must register for GST and lodge a BAS if your business has a GST turnover of $75,000 or more per year (or $150,000 or more for non-profit organisations). Once your turnover reaches or exceeds this threshold, registration is mandatory within 21 days.

Special case: taxi operators, rideshare drivers (Uber, DiDi), and similar services must register for GST regardless of their turnover level. There is no $75,000 minimum for this category.

Businesses with a turnover of less than $75,000 can voluntarily register for GST. The reason is to claim GST credits on your business purchases. If your purchases include significant GST (e.g., equipment or materials) and your sales are low, you may actually receive GST refunds by registering.

If you are not registered for GST, you do not lodge a BAS. You may still need to lodge an Instalment Activity Statement (IAS) if you are in the PAYG system or have FBT obligations, but that is a different, simpler form.

Do I Need to Lodge a BAS as a Sole Trader?

Yes, if you are a sole trader with a GST turnover of $75,000 or more, you must register for GST and lodge a BAS. The lodgment process for sole traders is typically done through myGov or through accounting software. Sole traders with a turnover under $75,000 who are not registered for GST do not need to lodge a BAS. Our BAS lodgment service for Adelaide sole traders covers the entire process if you prefer a registered BAS agent to handle it.

Do I Need to Lodge a BAS If I Have No Income?

If you are registered for GST and your reporting period is quarterly or monthly, you must lodge a BAS for every period, even if you had no income and no GST activity. A nil BAS (reporting zero) must still be lodged by the due date. Failure to lodge a nil BAS on time still attracts the FTL penalty ($330 per 28-day period).

BAS Labels Explained: What Each Code Means

The BAS uses letter-and-number codes (labels) to identify each reporting item. Here are the labels you will encounter on a standard quarterly BAS:

Types of BAS and Lodgment Frequencies

Quarterly BAS

The standard frequency for most Australian small businesses. Four lodgments per year covering the periods 1 July to 30 September (Q1), 1 October to 31 December (Q2), 1 January to 31 March (Q3), and 1 April to 30 June (Q4). All businesses with annual turnover under $20 million can use quarterly BAS unless they choose monthly.

Monthly BAS

Required for businesses with annual turnover of $20 million or more. Optional for smaller businesses that prefer to manage their GST cash flow monthly or that regularly claim GST refunds (for example, exporters). Monthly BAS is due on the 21st of the month following the reporting month.

Annual GST Return

Available to businesses with turnover under $75,000 that have voluntarily registered for GST and choose annual reporting. Annual returns are due by 28 February following the end of the financial year.

Instalment Activity Statement (IAS)

Not a BAS. The IAS is a separate, simpler form used by businesses that have PAYG instalment obligations but are not registered for GST (or for businesses that report GST annually but pay PAYG instalments quarterly). It covers only PAYG instalments and, if applicable, PAYG withholding. If you receive an IAS when you expected a BAS, it is because the ATO has determined your lodgment profile does not include GST quarterly reporting.

BAS Due Dates 2025-26

The quarterly BAS due dates are set by the ATO. If you lodge your own BAS (through myGov or Online services for business), the standard due dates apply. If you use a registered BAS agent, extended deadlines apply for Q1, Q3, and Q4 only. Q2 never gets an extended deadline regardless of whether you use an agent

If a BAS due date falls on a weekend or public holiday, the deadline moves to the next business day. For the complete current schedule, see the ATO activity statement due dates page.

How to Calculate Your BAS: Step-by-Step

For a quarterly BAS covering GST and PAYG withholding, the calculation involves four steps:

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  Step 1: Calculate GST collected on sales (G1). Total all sales invoices you issued during the quarter. If your prices include GST, divide by 11 to get the GST component. If your prices are GST-exclusive, multiply by 10% to get GST. Record the GST amount separately from the sales amount.
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  Step 2: Calculate GST credits on purchases (G10 and G11). Total all eligible business purchases during the quarter that included GST. Divide by 11 to get the GST credit amount. Only purchases with a valid tax invoice from a GST-registered supplier are eligible.
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  Step 3: Calculate net GST. Net GST = GST collected on sales minus GST credits on purchases. If GST collected exceeds GST credits, you pay the difference to the ATO. If credits exceed collected GST (common for exporters or businesses in a growth phase), you receive a GST refund.
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  Step 4: Add PAYG withholding (W2). Total the income tax you withheld from all employee wages and salaries during the quarter. This goes in label W2 and is added to your net GST as a separate payment.

Worked example:

In this example, the business owes $9,400 to the ATO for the quarter: $7,000 in net GST plus $2,400 in PAYG withholding. Both amounts are lodged on the same BAS and paid as a single payment.

How to Fill Out Your BAS

Most businesses complete their BAS using cloud accounting software (Xero, MYOB, or QuickBooks Online), which automatically calculates the BAS figures from the coded transactions in your books. If your bookkeeping is current and reconciled, the software generates a pre-filled BAS report that maps your data to the correct labels.

If you are completing a BAS manually:

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  G1: Enter the total value of all sales (including GST) you made during the period. Do not separate out the GST component here.
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  G2 and G3: Enter the value of export sales (G2) and other GST-free sales (G3) if applicable. These are subtracted from G1 to identify the taxable portion.
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  G10 and G11: Enter the total value of capital purchases (G10) and non-capital purchases (G11), both including GST where applicable.
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  W1: Enter the total gross salary and wages paid to employees. Do not include super (super is not a PAYG withholding obligation).
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  W2: Enter the PAYG withholding amount you deducted from employee wages. This is what you pay to the ATO on their behalf.

The ATO provides a worked example of the BAS form showing how the labels map to a completed form.

How to Lodge Your BAS

There are four main methods for lodging your BAS in 2025-26:

1. Online Services for Business (ATO Business Portal)

The ATO’s Online services for business (which replaced the old Business Portal in 2022) allows businesses to lodge, view, and amend activity statements directly. Access via your myGovID digital identity at onlineservices.ato.gov.au. This is the correct current method for businesses lodging their own BAS online. Note: the old Business Portal URL is no longer active. Do not try to lodge using the old portal address.

2. myGov (for Individuals and Sole Traders)

If you are an individual or sole trader, you can lodge your BAS through myGov (my.gov.au) after linking your ATO account. Under the ATO section, select ‘Manage’ then ‘Business Activity Statements’. This method gives you real-time access to your BAS history, due dates, and payment status.

3. Through Accounting Software (SBR)

Xero, MYOB, and QuickBooks Online (Australian version) all support Standard Business Reporting (SBR), which allows you to lodge your BAS directly from within the software. This is the most efficient method for businesses using cloud accounting: the software maps your coded transactions to the BAS labels, generates a pre-filled BAS, and you lodge in one step without re-entering data. For the step-by-step Xero BAS lodgment process, see our bookkeeping guide.

4. Through a Registered BAS Agent

A registered BAS agent prepares, reviews, and lodges your BAS on your behalf. This is the recommended approach if your books are complex, you are not confident in your GST coding, or you want access to the extended lodgment deadlines (Q1, Q3, Q4). A registered agent also provides professional accountability: if an error is made, you have a qualified professional’s oversight and the protections of the Tax Practitioners Board framework. Verify any BAS agent on the TPB register before engaging them.

The Kalculators are registered BAS agents. Our BAS lodgment service covers preparation, review, and lodgment for quarterly, monthly, and annual reporters.

BAS Penalties and Late Lodgment Consequences

The ATO’s failure-to-lodge penalty applies when a BAS is not lodged by the due date. For small businesses, the penalty is $330 per 28-day period (or part thereof) that the BAS is overdue, up to a maximum of $1,650 (five penalty units). This applies per BAS per period, so two overdue BAS lodgments accumulate separate penalties simultaneously.

Critical point: the FTL penalty applies to nil BAS lodgments as well. If you had zero activity for the quarter but are registered for GST and required to lodge, failing to lodge a nil BAS on time incurs the same penalty.

General Interest Charge (GIC)

If you lodge your BAS but do not pay the amount owing by the due date, the ATO charges General Interest Charge (GIC) on the unpaid amount at the current rate of 10.96% per annum, compounding daily from the day after the due date. From 1 July 2025, GIC is no longer deductible as a business expense, making late payment significantly more expensive than before.

How to Get a Penalty Remitted

If you have a legitimate reason for a late BAS (serious illness, natural disaster, or an administrative error), the ATO may remit (reduce or cancel) the FTL penalty. Contact the ATO on 13 28 66 (business enquiries) to discuss your circumstances. The ATO is generally more receptive to remission requests when: the late lodgment was isolated (not a pattern), the BAS was lodged before you contacted the ATO, and you paid any amount owing promptly.

BAS vs Tax Return: What's the Difference?

A BAS and a tax return are different documents with different purposes. They are both ATO obligations but serve distinct functions and are lodged on different schedules:

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  BAS: covers GST, PAYG withholding, and other tax obligations for a specific period (monthly or quarterly). Lodged throughout the year at regular intervals.
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  Income tax return: covers income, deductions, offsets, and the final income tax liability for the full financial year (1 July to 30 June). Lodged once per year, generally by 31 October or with a registered tax agent by up to 15 May the following year.
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  Is BAS the same as GST? Not exactly. BAS is the form you use to report and pay GST, among other taxes. GST is the tax itself. The BAS is also used to report PAYG withholding and other taxes unrelated to GST.
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  Is BAS the same as PAYG? No. PAYG (Pay As You Go) is a system that includes both PAYG withholding (tax deducted from employees) and PAYG instalments (prepayments of your own income tax). Both are reported and paid via the BAS or IAS, but they are separate from GST.

How The Kalculators Can Help With Your BAS

We are registered BAS agents providing BAS preparation and lodgment services for Adelaide small businesses and online across South Australia. Our BAS service covers:

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  Review and coding of all transactions for the period
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  GST reconciliation to confirm the BAS figures match the accounting records
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  Preparation of the BAS and lodgment through the ATO’s SBR system
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  Access to the extended agent lodgment deadlines for Q1, Q3, and Q4
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  Advice on GST treatment questions and corrections to prior-period errors

If your BAS is behind or if you have discovered errors in prior lodgments, we handle catch-up lodgments and amendments. For businesses new to GST, our bookkeeping setup service configures your chart of accounts and GST tax codes from day one so your BAS figures are always accurate.

Call (08) 7480 2593, Monday to Friday, 9:00 AM to 6:00 PM. Offices at 182 Salisbury Highway, Salisbury; 315 Prospect Road, Blair Athol; and 280 Main South Road, Morphett Vale. BAS agent services online for Murray Bridge, Woodville, Melrose Park, Port Augusta, Prospect, and Brighton via info@thekalculators.com.au.