When is the July to September 2026 BAS due?

The standard due date is Wednesday 28 October 2026. If you lodge online yourself and qualify for the two-week concession, you have until 11 November 2026. If a registered tax or BAS agent lodges an eligible BAS electronically, it's 25 November 2026. Always check the date shown on your own statement.

Does the extension apply to the October to December quarter?

No. The December quarter BAS is due 28 February 2027, which already includes extra time, and neither the two-week concession nor the agent program pushes it later.

What interest does the ATO charge on a late BAS payment?

The general interest charge is 11.51% a year for October to December 2026, compounding daily. GIC incurred on or after 1 July 2025 is not tax deductible.

Should I lodge my BAS if I can't pay it?

Yes. The ATO recommends lodging on time even if you can't pay in full, then paying what you can or setting up a payment plan. Debts of $200,000 or less can usually be put on a plan online.

Is there a penalty if my BAS is a refund or nil?

The ATO generally doesn't apply the failure to lodge penalty when a late BAS has a nil or refund result, but you should still lodge on time. A refund can't be paid until the BAS is lodged.

BAS Due Date 28 October 2026: Q1 Guide

Key dates for the July to September 2026 quarter

This is the first quarter of the 2026–27 financial year. Depending on how your BAS is lodged, one of these three dates will apply:

28 OctStandard due date to lodge and pay
11 NovIf you lodge online yourself and qualify for the two-week concession
25 NovIf an eligible BAS is lodged electronically by a registered tax or BAS agent

The due date printed on your activity statement, or shown in ATO online services, is the one that counts. If a due date falls on a weekend or public holiday, you can lodge and pay on the next business day. Monthly BAS works differently: it's due on the 21st of the following month, and none of the extensions below apply. ATO: due dates for lodging and paying your BAS

Lodging online yourself: the two-week concession

If you receive your BAS and lodge it online, through Online services for business or, for sole traders, myGov, you may automatically get an extra two weeks to lodge and pay. For this quarter, that moves the deadline from 28 October to 11 November 2026.

You don't need to apply. The later date appears in online services once your statement is generated.
It applies to quarterly BAS for the September, March and June quarters. The December quarter (due 28 February) already has extra time built in.
It doesn't apply to monthly activity statements or to quarterly instalment notices (forms R, S and T).

ATO: two-week lodgment concession terms and conditions

Using a registered tax or BAS agent: 25 November

Under the ATO's 2026–27 lodgment program for registered agents, an eligible quarterly BAS for July to September that the agent lodges electronically is due on 25 November 2026.

The concession generally needs your previous activity statement to have been lodged electronically. A paper lodgment doesn't get the later date.
It covers the September, March and June quarters only. Your agent can confirm the exact date that applies to you.

Your agent still needs reconciled records in good time to prepare and check the return. ATO: registered agent lodgment program, activity statements

What happens if you lodge or pay late?

Interest on unpaid amounts. The ATO charges the general interest charge (GIC) on any amount not paid by the due date. For October to December 2026 the rate is 11.51% a year (0.03153425% a day), compounding daily. As a rough illustration, $5,000 left unpaid for 30 days at that rate would add about $47.50 in GIC. ATO: general interest charge rates

No tax deduction for that interest. GIC incurred on or after 1 July 2025 is no longer deductible, so a late payment now costs you the full amount. ATO: denying deductions for ATO interest charges

Failure to lodge on time penalty. For a small business, this penalty is one penalty unit for every 28 days (or part of 28 days) the BAS is late, up to a maximum of five units. The ATO generally sends a reminder first and generally doesn't apply the penalty when a late BAS shows a nil amount or a refund. ATO: failure to lodge on time penalty

Can't pay the full amount? Lodge on time anyway

A common mistake is holding back the BAS because the money isn't there. The ATO's advice is to lodge on time even if you can't pay, and to get in touch before the due date. Lodging on time keeps your account up to date, shows exactly what you owe and avoids the failure to lodge penalty.

If you owe $200,000 or less, you may be able to set up a payment plan yourself online without speaking to anyone.
An up-front payment is required to set up a payment plan, and GIC keeps accruing on the unpaid balance, so a shorter plan costs less.
The ATO's payment plan estimator can help you work out repayments you can realistically keep up with.

ATO: what if you can't lodge and pay on time

A quick checklist before you lodge

Reconcile every bank, credit card and payment account (Stripe, Square, PayPal) to 30 September.
Check GST coding on sales and purchases, especially GST-free items, overseas subscriptions and anything with private use.
Keep the tax invoices for purchases you're claiming GST credits on.
Make sure PAYG withholding on the BAS agrees with what your payroll reported through Single Touch Payroll.
Find your payment reference number (PRN) so the payment goes to the right account.
Set aside GST and PAYG withholding each month from now on, so the December quarter is less of a shock.

How Bookfix can help

Bookfix is a CPA-led online practice based in Sydney, working with small businesses and sole traders across Australia. We reconcile your quarter in Xero, QuickBooks or MYOB and prepare your BAS. All tax and BAS work is reviewed and lodged by our supervising registered tax agent. BAS is from $250 + GST, and bookkeeping is from $100/month + GST for turnover up to $80k. If you're a few quarters behind, see catch-up bookkeeping.

Sources

Checked against ato.gov.au on 25 October 2026.

Want this quarter's BAS off your plate? Email us for a quick quote. We're usually back to you within 30 minutes, and all tax and BAS work is reviewed and lodged by our supervising registered tax agent.

This article is general information only, current as at 25 October 2026. It isn't personal financial or tax advice, so check how the rules apply to your business before you act.

BAS due 28 October 2026: key dates, extensions and what to do if you can't pay