What Is a BAS? Lodgement Guide (2025-26)

A Business Activity Statement, or BAS, is the form most GST-registered Australian businesses use to report and pay several tax obligations to the Australian Taxation Office. For many small businesses, the BAS is part of the regular compliance cycle, along with paying employees and keeping records up to date. Depending on your registration and business circumstances, a BAS can include GST collected on sales, GST credits on business purchases, PAYG withholding from employee wages, PAYG instalments, and in some cases other obligations such as wine equalisation tax or luxury car tax. Even if your business has had little activity, you may still need to lodge a BAS or a nil activity statement if the ATO has told you to do so.

For most businesses, BAS reporting is either quarterly or monthly. Quarterly lodgers usually report for July to September, October to December, January to March, and April to June. For the 2025-26 year, the quarterly BAS due dates are 28 October 2025, 28 February 2026, 28 April 2026 and 28 July 2026. If you lodge through a registered tax or BAS agent, you generally receive extra time, and those extended due dates are usually one month later for quarterly BAS lodgements, provided you are eligible and the statement is lodged through the agent. Monthly BAS lodgers generally need to lodge and pay by the 21st day of the following month. If the due date falls on a weekend or public holiday, the ATO usually allows lodgement on the next business day, but it is still best to aim early so your bank processing time does not cause a late payment.

Lodging online is usually the easiest option. Most small businesses can use Online services for business through myGovID and Relationship Authorisation Manager, or lodge via their registered tax or BAS agent software. Some businesses still receive paper BAS forms, but online lodgement is faster, reduces errors, and gives you access to previous statements and pre-fill information. If you use accounting software connected to the ATO, the figures can often flow straight from your bookkeeping records into the BAS, which saves time and reduces the chance of typing mistakes. Before lodging, check that your bank details, GST registration status, PAYG withholding registration, and bookkeeping reconciliations are all correct, because mistakes in these areas can create cash flow problems and ATO follow-up.

GST on a BAS is often the biggest focus for business owners. GST is generally 10% on taxable sales, and you report the GST you collected from customers and the GST credits you can claim on eligible business purchases. The BAS does not ask for every invoice individually; instead, you report totals for the period, usually at either the cash basis or accruals basis depending on how your business is set up. If your sales include GST-free or input-taxed items, those are treated differently and should not be mixed up with taxable sales. It is important to keep valid tax invoices for your expenses, because without proper records you may lose GST credits. For businesses with mixed private and business use, only the business portion of the expense is claimable, so accurate recordkeeping matters.

PAYG reporting is another key part of the BAS for employers and some businesses with tax instalments. If you pay employees, your BAS includes the amount of PAYG withholding deducted from wages and salaries, which is then remitted to the ATO. This is separate from superannuation, which is not paid through the BAS. Some businesses also have PAYG instalments, which are regular prepayments towards expected income tax. These instalments help spread tax payments through the year instead of leaving a large bill at tax return time. If your turnover or income changes significantly, you may be able to vary PAYG instalments, but this should be done carefully to avoid underpayment penalties.

The most common BAS problems are late lodgement, poor bookkeeping, mixing business and private spending, and failing to keep enough cash aside for GST and PAYG amounts that are collected on trust for the ATO. Late lodgement can trigger failure to lodge on time penalties and, in some cases, general interest charge on unpaid amounts. The ATO also uses compliance activity to identify businesses that consistently lodge late or report inconsistently. The best way to avoid trouble is to reconcile your bookkeeping regularly, set aside GST from each payment you receive, keep payroll records current, and use reminders well before each due date. If you cannot pay on time, lodge by the due date anyway and contact the ATO or your tax agent to discuss payment options, because lodging late and paying late can create different problems.

If you want help understanding your BAS obligations, checking your GST or PAYG reporting, or getting your lodgements back on track, contact SolAeon Tax for tailored advice.