Lodging a BAS is not the hard part. The hard part is leaving it to the night before and then hunting for numbers that should have been sitting in your books the whole time. Keep the bookkeeping current through the quarter and the actual lodgment takes about ten minutes.
Here is what the form wants, how to send it, and when it is due.
What you are actually reporting
A BAS pulls a few separate obligations onto one form. If you want the full picture of what a BAS is, we cover that on its own. The short version:
The GST you collected on sales, less the GST you paid on purchases. That difference is labels 1A and 1B, and it nets to one number.
The PAYG you withheld from wages and other payments, at W1 and W2.
A PAYG instalment toward your own income tax, if the ATO has put you in that system, at 5A or T7.
Add it up and you get a single figure: an amount to pay, or a refund coming back.
Get your books straight first
This is where the ten-minute lodgment is won or lost. Reconcile your bank so every sale and expense is coded and the GST on each line is right. When your books are current, your software fills most of the BAS labels for you and there is nothing left to chase.
Have your records on hand too. You need a valid tax invoice to claim a GST credit on any purchase of $82.50 or more including GST. Keep the lot for 5 years.
How to lodge
You have a few channels, and they are all faster than paper.
If you run a company, trust or partnership, use Online services for business.
If you are a sole trader, lodge through myGov linked to ATO online services.
SBR-enabled accounting software lodges straight from your coded transactions. Xero, MYOB and QuickBooks all do this, so the figures you kept all quarter become the BAS with a couple of clicks.
HPLedger prepares your BAS from the same coded books and produces the figures and workpaper to file. It is not a registered STP lodger, so you send the finished figures through one of the channels above.
A registered tax or BAS agent can lodge for you, and there is a real bonus to that one, covered below.
A nil BAS still has to go in. You can lodge it online in seconds, or through the ATO automated phone line.
When it is due
Your reporting cycle sets the deadline.
Quarterly is the common one, for businesses with GST turnover under $20 million. The dates are 28 October, 28 February, 28 April and 28 July. Lodge online or through an agent and most quarters give you an extra 2 weeks. The exception is the December quarter, due 28 February, which already has a month built in, so no further extension applies there.
Monthly applies if your turnover is $20 million or more, or if you choose it. It falls due on the 21st of the following month, with no extension.
Annual is for businesses that voluntarily registered and stay under $75,000 turnover, or $150,000 for not-for-profits. It goes in with your tax return, or by 28 February if you have no return to lodge.
If a due date lands on a weekend or public holiday, you have until the next business day.
Figure 1. Your reporting cycle sets the deadline. Late lodgment triggers a penalty even on a nil or refund BAS.
If you are going to be late
Lodge anyway. The penalty is for failing to lodge, not for failing to pay, and the two are treated separately.
Failure to Lodge hits at 1 penalty unit for every 28 days the BAS is overdue, or part of that period, capped at 5 units for a small business. The penalty unit rose to $364 on 1 July 2026, so that cap is now $1,820. It applies even when the BAS is nil or a refund.
If you owe money and cannot pay by the date, still lodge on time, then call the ATO and set up a payment plan. General Interest Charge runs on the unpaid balance, compounds daily, sits around 10.65% a year, and since 1 July 2025 you can no longer deduct it. Paying late is expensive. Lodging late is expensive and avoidable.
The technical detail
- BAS framework: activity statements under Division 388, Schedule 1, Taxation Administration Act 1953. GST reported under the A New Tax System (Goods and Services Tax) Act 1999; PAYG withholding and instalments under Schedule 1, TAA 1953.
- Quarterly due dates 2025-26: Q1 (Jul to Sep) 28 Oct 2025; Q2 (Oct to Dec) 28 Feb 2026; Q3 (Jan to Mar) 28 Apr 2026; Q4 (Apr to Jun) 28 Jul 2026. Lodging online or via a registered agent extends most quarters by about 2 weeks; Q2 already carries a one-month extension and is not extended further. Monthly: 21st of the following month, no concession. Annual GST return: with the tax return, or 28 Feb where no return is due.
- Reporting cycles: quarterly if GST turnover is under $20m; monthly if $20m or more, or by choice; annual only for voluntary registrants under $75,000 ($150,000 for not-for-profits).
- GST credit substantiation: a valid tax invoice is required for purchases of $82.50 or more, GST-inclusive. Records retained 5 years.
- Failure to Lodge penalty: 1 penalty unit per 28 days or part, capped at 5 units for a small business. The penalty unit is $364 for matters on or after 1 July 2026, indexed up from $330; the small-business cap is therefore $1,820. Applies to nil and refund statements.
- General Interest Charge: applied to unpaid amounts, compounding daily; approximately 10.65% per annum for the January to March 2026 quarter, reset quarterly. GIC is not tax deductible for periods from 1 July 2025.
Dated to 2 July 2026. Rates and thresholds change; confirm current figures with the ATO or your registered agent before relying on them.
