Business Activity Statements (BAS): An overview

A Business Activity Statement (BAS) is a form submitted to the Australian Taxation Office (ATO) to report and pay several tax obligations, including GST, PAYG instalments, PAYG withholding, and fringe benefits tax. If your business is registered for GST — required once turnover reaches $75,000, or $150,000 for not-for-profits — you need to lodge a BAS, typically every quarter (ATO, 2025).

Australia has 2.73 million actively trading businesses, 97.3% of which are small (ABS/ASBFEO, 2025). For those registered for GST, BAS is a recurring compliance task — yet many business owners still treat it as a quarterly scramble rather than an ongoing part of running their business. With the right setup, BAS preparation can happen progressively across the quarter, so lodgement day becomes a final review rather than a last-minute scramble.

This article covers what BAS is, what to include, when it's due, how to prepare and lodge, common mistakes, and how accounting software can help you stay on top of it.

What is a Business Activity Statement (BAS)?

A Business Activity Statement is the form Australian businesses use to report and pay tax obligations to the ATO. It covers GST collected and paid, PAYG withholding from employee wages, PAYG income tax instalments, and other taxes depending on your business activities.

Who needs to lodge a BAS

You need to lodge a BAS if your business is registered for GST. GST registration is compulsory once your annual turnover reaches $75,000, or $150,000 for not-for-profit organisations (ATO, 2025). Below those thresholds, GST registration is voluntary — but if you've registered voluntarily, you still need to lodge.

BAS lodgement frequency

How often you lodge depends on your turnover and registration status:

• Quarterly: most small businesses with GST turnover under $20 million lodge quarterly. This is the default frequency the ATO assigns.

• Monthly: businesses with GST turnover of $20 million or more must lodge monthly. You can also choose monthly if you prefer more frequent reporting.

• Annually: voluntary GST registrants with turnover under $75,000 may be eligible to lodge annually, aligned with their income tax return due date.

Your BAS covers all tax obligations for that reporting period in a single form (ATO, 2025).

What is an Instalment Activity Statement (IAS)?

An Instalment Activity Statement is a simpler form for businesses that need to report PAYG withholding or PAYG income tax instalments but are not registered for GST.

The key difference: a BAS covers GST plus other obligations in one form. An IAS covers only PAYG obligations — no GST component.

If you're registered for GST, your PAYG obligations are included in your BAS, so you won't receive a separate IAS. You'll only get an IAS if you have PAYG obligations but no GST registration.

What to include in a BAS

Your BAS includes every tax obligation your business is registered for during that period. The specific sections you need to complete depend on your registrations:

• Goods and Services Tax (GST) — the 10% tax on most goods and services sold in Australia. You report GST collected on sales and GST paid on business purchases, with the difference owed to (or refunded by) the ATO.

• PAYG income tax instalments — regular prepayments toward your expected annual income tax liability, helping you avoid a large year-end tax bill.

• PAYG withholding — tax withheld from payments to employees, directors, and some contractors, which you remit to the ATO on their behalf.

• Fringe benefits tax (FBT) — tax on non-cash benefits provided to employees, such as company cars or private health insurance.

• Luxury car tax (LCT) — applies if your business sells or imports luxury vehicles above the LCT threshold.

• Wine equalisation tax (WET) — applies to wine producers, wholesalers, and importers.

• Fuel tax credits — credits you can claim for fuel used in business activities such as machinery, heavy vehicles, or off-road equipment.

Not every business completes every section. The ATO pre-populates your BAS with only the labels relevant to your registrations (ATO, 2025).

BAS due dates and lodgement frequency

The standard quarterly BAS due dates for most small businesses are:

If you lodge monthly, your BAS is due on the 21st of the following month.

If you lodge annually, your due date aligns with your income tax return — generally 31 October for most taxpayers, or later if you lodge through a registered tax agent (ATO, 2025).

Which lodgement frequency applies to your business

• Under $75,000 turnover (voluntary GST registration): you may be eligible to lodge annually.

• $75,000 to under $20 million turnover: quarterly (standard assignment for most small businesses).

• $20 million or more turnover: monthly lodgement is mandatory.

If you can't lodge by the deadline, contact the ATO before the due date to discuss options. Lodging late without prior arrangement may result in a Failure to Lodge penalty (ATO, 2025).

If you're a sole trader, the same BAS obligations apply once you're registered for GST — see our dedicated sole trader BAS guide for specifics.

How to prepare your BAS

BAS preparation is simpler when your bookkeeping happens across the quarter rather than in one burst before the deadline. Here's a practical walkthrough:

1. Reconcile your transactions throughout the quarter

Connect your bank feeds and reconcile transactions as they come in — weekly or even daily. This is the single step that makes the biggest difference. When transactions are categorised correctly as they arrive, you avoid the end-of-quarter backlog of matching hundreds of entries at once.

The friction point for many business owners is manual bank reconciliation — downloading bank statements, matching them line by line, and hoping nothing slips through. Accounting software that imports bank transactions automatically and suggests category matches can help reduce this manual work.

2. Review your BAS report

Once your transactions are reconciled, generate your BAS report from your accounting software. Check that:

• GST collected and GST paid figures match your expectations

• PAYG withholding totals align with your pay runs

• No uncategorised transactions are skewing your figures

3. Check your bank balance against your obligation

Before lodging, compare the amount you owe on your BAS with your available cash. If you owe GST and PAYG, that money needs to be available by the due date. Setting aside your estimated BAS obligation in a separate account across the quarter — even a rough percentage of revenue — helps avoid cash flow surprises at lodgement time.

4. Run a profit and loss statement

A profit and loss report for the same period gives you a cross-check. If your BAS figures look inconsistent with your revenue and expenses, something may need investigating before you lodge. A balance sheet reconciliation before BAS can also help catch mismatches in GST clearing accounts.

5. Keep preparation progressive

The businesses that find BAS straightforward are the ones that don't save it all for deadline week. Reconciling regularly, reviewing categorisation as you go, and checking in on your figures monthly means your BAS report is easier to review when the quarter ends. Preparation across the quarter is what turns BAS from an obligation into a routine check.

How to prepare BAS in MYOB Business

MYOB Business can help prepare your BAS or IAS using your reconciled transaction data and tax code setup. Once your bank feeds are imported and transactions are categorised, MYOB uses your tax codes to calculate the figures that appear on your activity statement.

Before submitting, review your BAS report for:

• Tax invoices for purchases over $82.50, including GST, where you're claiming GST credits

• Uncategorised transactions that may be skewing your GST position

• Unusual GST treatment — items coded differently from how you'd expect

Once you're satisfied the figures are accurate, you can proceed to lodge. A registered tax agent or BAS agent can also access your MYOB file to review and lodge on your behalf.

How to lodge your BAS

Once your BAS is prepared and reviewed, you can lodge using several methods:

1. Online through your accounting software — SBR-enabled software (including MYOB Business) supports BAS preparation and lodgement workflows from your accounting platform.

2. ATO Online Services for business — access via myID and Relationship Authorisation Manager (RAM) to lodge directly with the ATO. Sole traders may also access ATO services through myGov.

3. Through a registered tax agent or BAS agent — they can prepare and lodge on your behalf and may also receive extended lodgement deadlines.

4. By phone — for simple BAS forms with limited labels, the ATO offers a phone lodgement service.

For full details on each lodgement method, see the ATO's lodgement guide.

BAS form example

The BAS form uses a label system with letters and numbers to identify each field. Key labels you'll encounter:

• 1A — GST on sales (the total GST you've collected)

• 1B — GST on purchases (the GST you've paid on business expenses)

• G1 — total sales for the period (including GST-free sales)

• G10 — capital purchases for the period

• G11 — non-capital purchases for the period

• W1 — total amounts subject to PAYG withholding

• W2 — amounts withheld from payments (the tax you've held from employees)

• T1/T4 — PAYG income tax instalment fields

Accounting software can help populate these figures from your reconciled transactions into your BAS report for review before lodgement.

For the full form and label explanations, see the ATO's BAS information page.

Common BAS mistakes to avoid

Most BAS errors come from the same handful of issues — and they tend to compound when preparation is left to the last minute:

1. Mixing personal and business transactions — using one bank account for both means GST may be claimed on personal purchases, which the ATO can flag during review.

2. Incorrect GST coding — coding a GST-free item (like basic food or exports) as taxable, or missing GST on a taxable purchase. This inflates or understates your GST position.

3. Missing the lodgement deadline — the ATO may issue a Failure to Lodge penalty if your BAS is overdue. Contact them before the due date if you need more time.

4. Not reconciling before lodging — submitting a BAS with unreconciled transactions means your figures may not reflect actual business activity, leading to amendments later.

5. Claiming GST on GST-free items — items like basic food, some medical services, and exports don't include GST. Claiming credits on these items can lead to incorrect BAS figures or follow-up questions.

Keeping records up to date across the quarter — rather than reconciling everything in deadline week — helps catch these errors before they reach your BAS. For a deeper look at common GST issues, see top 10 common GST mistakes in BAS reports.

How do IAS and BAS help your business?

Beyond meeting your tax obligations, BAS and IAS give you a structured rhythm for reviewing your business finances. Every lodgement period forces you to reconcile transactions, review cash flow, and check that your records match reality.

When you track GST, PAYG, and expenses throughout the quarter using software, BAS becomes less of an obligation and more of a regular financial checkpoint. You can see whether your GST credits are growing (which may signal increased investment), whether withholding is tracking with headcount changes, and whether your income tax instalments still match your actual revenue.

This regular cadence is where the real value sits. Businesses that use BAS preparation as ongoing financial tracking — rather than a quarterly paperwork exercise — tend to catch discrepancies earlier and make more informed decisions about spending, hiring, and cash reserves. For more on building good financial habits, see our guide to small business accounting.

Prepare and lodge your BAS with MYOB

BAS confidence doesn't come from scrambling at the end of the quarter — it comes from knowing your records have been kept up to date throughout the quarter. When your bank feeds are connected, transactions are reconciled as they arrive, and your GST coding is reviewed progressively, lodgement day becomes a final check rather than a frantic catch-up.

MYOB Business supports BAS preparation and lodgement workflows — part of a broader AI accounting approach that helps reduce manual admin.

MYOB’s AI BAS (Beta), available to eligible non-employing MYOB Business Lite and Pro customers in Australia, flags missing documents, GST issues, and transactions that need attention as they happen. You stay in control and check your figures before you lodge with the ATO.

"Less than half what I used to spend for the BAS — because previously I was doing manual reconciliation, and now it's automated." — Suresh Patel, MYOB Business customer (2026)

90% of MYOB Business customers are confident their records are BAS-ready (survey of 319 MYOB Business customers, Nov 2025).

Try MYOB today!

Frequently asked questions

Is BAS the same as income tax?

BAS and income tax are separate obligations. A BAS reports GST, PAYG withholding, and PAYG instalments — typically quarterly. Income tax is a separate annual obligation calculated on your total taxable income for the financial year. Your PAYG instalments (reported on your BAS) are prepayments toward that annual income tax bill, but the BAS itself is not your income tax return.

Do you get money back from BAS?

Yes — if your GST credits (GST paid on business purchases) exceed the GST you collected on sales during the period, the ATO refunds the difference. This is common for businesses that make large capital purchases or have significant GST-free sales. Processing times can vary, so check ATO guidance for current timeframes.

What happens if I lodge my BAS late?

The ATO may charge a Failure to Lodge (FTL) penalty, calculated at one penalty unit for each 28-day period your BAS is overdue, up to a maximum of five penalty units. If you know you can't lodge by the deadline, contact the ATO before the due date — they may grant additional time or waive the penalty for first-time late lodgers with a reasonable explanation (ATO, 2025).

Can my accountant or bookkeeper lodge my BAS for me?

Yes — registered tax agents and BAS agents can prepare, review, and lodge your BAS on your behalf. They may also receive extended lodgement deadlines from the ATO. If you're unsure whether your bookkeeper can lodge, check they're registered with the Tax Practitioners Board — only registered agents can lodge BAS for a fee. For help choosing the right professional, see how to decide between hiring a bookkeeper or an accountant.

Information provided in this article is of a general nature and does not consider your personal situation. It does not constitute legal, financial, or other professional advice and should not be relied upon as a statement of law, policy or advice. You should consider whether this information is appropriate to your needs and, if necessary, seek independent advice. This information is only accurate at the time of publication. Although every effort has been made to verify the accuracy of the information contained on this webpage, MYOB disclaims, to the extent permitted by law, all liability for the information contained on this webpage or any loss or damage suffered by any person directly or indirectly through relying on this information.

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