What Is a BAS, and Does My Business Need to Lodge One? A Plain-English Guide

Last updated: 25 October 2026.

BAS stands for business activity statement. It is the form businesses use to report and pay certain taxes to the ATO, most commonly GST and PAYG withholding. Many new owners hear “you need to lodge a BAS” without anyone explaining what it is, whether it applies to them, or when it is due.

This guide answers those three questions in plain English. Every rule below was checked against ATO pages on 25 October 2026. It is general information, not advice about your particular situation.

The short version: if your business is registered for GST, you need to lodge a BAS. Registration is required once your GST turnover reaches A$75,000 (A$150,000 for non-profit organisations), and you must register within 21 days of reaching it. Most small businesses report quarterly, with due dates on 28 October, 28 February, 28 April and 28 July.

What is a BAS?

The ATO says that if you are a business registered for GST, you need to lodge a BAS. Your BAS helps you report and pay your goods and services tax (GST), PAY as you go (PAYG) instalments, PAYG withholding tax and other taxes. The ATO’s BAS hub also covers fringe benefits tax instalments, luxury car tax, wine equalisation tax and fuel tax credits, but most small businesses only deal with GST, PAYG withholding and PAYG instalments.

In simple terms, GST you collected on sales, less GST you paid on business purchases (your GST credits), is reported on the BAS. If you collected more than you paid, you pay the difference to the ATO. If you paid more than you collected, you may receive a refund. If you employ staff, the tax you withheld from their pay is reported on the BAS too.

Does my business need to lodge one?

For GST, the test is registration. You must register for GST in these situations, according to the ATO:

  • Your GST turnover (your business income, not profit, less certain amounts such as GST included in sales) is A$75,000 or more.
  • You are starting a new business and expect your turnover to reach A$75,000 in the first year.
  • Your non-profit organisation has a GST turnover of A$150,000 a year or more.
  • You provide taxi or limousine travel for passengers, including ride-sourcing, regardless of turnover.
  • You earn income through the sharing economy or digital platforms, such as food delivery services or other platform-based work.
  • You want to claim fuel tax credits.

If none of these apply, registering is optional. If you choose to register, generally you must stay registered for at least 12 months.

How GST turnover is measured

You reach the threshold if either your current GST turnover (the current month plus the previous 11 months) or your projected GST turnover (the current month plus the next 11 months) is likely to be A$75,000 or more. Check each month. Once you reach the threshold you have 21 days to register. If you should have registered and did not, the ATO says you may have to pay GST on sales made since the date you were required to register, even if you did not include GST in the price, and you may face penalties and interest.

If you are not registered for GST

You do not lodge a BAS for GST. However, other obligations can still put you on activity statements or instalment notices. The ATO says PAYG instalments are reported and paid through an activity statement or instalment notice, and PAYG withholding is reported on the BAS. Check your ATO online services for what you have been issued. Sole traders and small employers are often surprised by this.

How often do I lodge?

Reporting cycleWhoDue date
QuarterlyGST turnover under A$20 million, unless the ATO has told you to report monthly28 October, 28 February, 28 April, 28 July
MonthlyGST turnover of A$20 million or more, or directed by the ATO. You can also choose monthly if under A$20 million21st of the following month
AnnualVoluntarily registered, and GST turnover under A$75,000 (A$150,000 for NFPs)31 October (the ATO lists a 28 February alternative in some cases, and different dates may apply through an agent)

The quarterly dates are: July to September due 28 October; October to December due 28 February; January to March due 28 April; April to June due 28 July. The ATO says that if you lodge online you may be eligible for an extra two weeks to lodge and pay your quarterly BAS, and you may also get extra time if you lodge through a registered BAS agent. That extra time does not apply to the October to December quarter, because its due date already includes a one-month extension. If a due date falls on a weekend or public holiday, you have until the next business day. See our guide on BAS due dates for 2026-27 for the full set.

Switching cycle is possible. The ATO says you can generally start a new cycle straight away if you change early in the lodgment period, otherwise it starts from the next quarter or year, and you may be ineligible to change again if you changed within the last 12 months.

Cash or accruals: when GST is reported

There are two methods of accounting for GST. On a cash basis you report GST in the period you receive or make payment; on a non-cash (accruals) basis you report it in the period you issue or receive the invoice or payment, whichever happens first. The ATO says businesses with aggregated turnover under A$10 million can choose either method, and that the cash method keeps your cash flow better aligned with your BAS liabilities. The method affects when GST appears on your BAS, so your bookkeeping needs to use the same one consistently.

How to lodge

  • Online. Through Online services for individuals and sole traders (myGov), Online services for business, or SBR-enabled accounting software. The ATO says online lodgment lets you review your BAS before lodging.
  • Through a registered BAS agent. An agent can lodge, vary and pay on your behalf. Entities with an ABN other than sole traders must nominate a new registered agent in Online services for business, and the agent then has 28 days to add you as a client.
  • By mail. If you use a paper BAS, return the original form the ATO sends you.

Always pay in full by the due date to avoid the general interest charge. If you cannot lodge or pay on time, the ATO says to contact it or your registered agent before the due date. If you owe A$200,000 or less, you may be able to set up a payment plan online.

Nothing to report? You still lodge

The ATO says that even if you have nothing to report for the period, you still need to lodge your BAS as “nil” by the due date. If you have been lodging nil for a while, consider whether you still need to be registered. Cancelling when you no longer need the registration stops further BAS, but make sure all lodgment, reporting and payment obligations are met first.

Common BAS problems

  • Claiming GST credits without a valid tax invoice. You need a tax invoice for purchases over A$82.50 including GST. The ATO says you have four years to claim credits, so there is no need to claim before you hold the invoice.
  • Counting a purchase twice, or classifying a GST-free sale or purchase as taxable (or the reverse). These are examples the ATO gives of BAS mistakes.
  • Using the wrong period or method for cash and accruals.
  • Missing the 21-day registration window.
  • Leaving it late. If you are behind, see our catch-up plan for overdue bookkeeping and BAS.

The ATO says most GST mistakes can be fixed in your next BAS, and where that is not possible you lodge a revision. Keeping your books reconciled monthly is the best way to avoid them. Our guide on what documents to give your BAS agent lists what a BAS agent needs from you.

How we help

Our team includes a registered BAS agent. We prepare and lodge BAS for Sydney small businesses and not-for-profits, keep the books it relies on, and remind you before each due date. See our BAS agent services and bookkeeping services, or email info@guidancegrowth.com.au or use our get in touch page.

Frequently asked questions

What does BAS stand for?

BAS stands for business activity statement. It is the ATO form you use to report and pay GST, PAYG withholding, PAYG instalments and other taxes.

Do I need to lodge a BAS if I am not registered for GST?

You do not lodge for GST if you are not registered. The ATO says registration is required at a GST turnover of A$75,000 (A$150,000 for non-profit organisations), and optional below that. Other obligations, such as PAYG withholding and instalments, can still be reported on an activity statement or instalment notice, so check your ATO online services.

When is my BAS due?

Quarterly BAS is due on 28 October, 28 February, 28 April and 28 July. Monthly BAS is due on the 21st of the following month. Online lodgment or lodging through a registered BAS agent may give extra time on quarterly BAS, but not for the October to December quarter.

Do I have to lodge a BAS if I had no sales?

Yes. The ATO says you still need to lodge a nil BAS by the due date if you are registered. If you have nothing to report for a while, consider whether you still need to be registered.

How soon must I register for GST?

The ATO says you must register within 21 days of your GST turnover reaching the threshold. Check each month, using both your current and your projected turnover.

Can a bookkeeper lodge my BAS?

Only if they are a registered BAS agent. The Tax Practitioners Board requires registration for anyone providing BAS services for a fee or other reward.

Sources and further reading

This article is general information, not personal advice. Rules and dates can change, so check ato.gov.au or acnc.gov.au for the latest, or speak to us about your situation.

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