The July–September activity statement is due on 28 October - or 25 November if a registered agent lodges it for you. It is also, this year, a first in two ways: the first BAS covering a full quarter of Payday Super, and the first with a full quarter of the new award rates in the PAYG withholding figures. Both change what “reconciled” means. Here is the checklist we work through before lodging a Q1 BAS, in the order that catches the most errors.
1. Bank reconciliation to 30 September - complete, not “mostly”
Every account that touches the business: operating accounts, credit cards, loan accounts, the clearing-house account if your super provider holds funds in transit. An unreconciled line is an unclassified transaction, and an unclassified transaction is a GST figure the BAS cannot see. If the reconciliation report shows anything older than the quarter, resolve it before you go further; the BAS is only as good as the ledger beneath it.
2. GST coding: the five traps that show up every October
- GST-free and input-taxed items coded as taxable - bank fees, interest, most insurance stamp duty, residential rent, some food and medical items. Over-claiming here is the most common ATO adjustment we see.
- Overseas subscriptions and software - many now carry GST, many do not. Check the invoice, not the assumption.
- Capital purchases coded as expenses - a vehicle or equipment purchase belongs at G10, not G11, and the asset register needs the entry too.
- Wages, super and PAYG coded with GST - none of them carry it. A payroll journal with the wrong default tax code quietly inflates G11 all quarter.
- Private use - a vehicle, phone or home-office cost claimed at 100% when the business-use estimate is lower.
A ten-minute scan of the GST audit report sorted by tax code finds most of these. Then confirm the method: cash or accruals must match what you are registered for, and it must match last quarter.
3. PAYG withholding: tie W1 and W2 to STP, not to the payroll summary
W1 is gross wages paid in the quarter; W2 is the tax withheld. Both should agree to what you reported to the ATO through STP for the same period - the ATO pre-fills and data-matches these, and a difference is the fastest way to a please-explain. This quarter the award increase from 1 July changed gross wages for most employees; if a rate was updated late and back-paid, make sure the back-pay sits in the quarter it was paid.
4. Super: reconcile what was paid per payday, not what was accrued
Super no longer appears on the BAS, but Q1 is the first quarter the ATO can see, per pay run, whether contributions reached the fund within seven business days. Before you lodge, run three totals side by side: super reported through STP for 1 July to 30 September; super the clearing house shows as received by funds; and super accrued in the ledger. They should be the same number. If contributions are still sitting in transit or were rejected and not resubmitted, fix that this week - the first-90-days brief covers how the ATO is treating late payments in year one.
5. The PAYG instalment decision at T7
If you pay PAYG instalments, the ATO’s pre-filled amount is based on last year’s return. Q1 is the right time to decide whether it still fits. If income is tracking materially above or below last year, you can vary the instalment - but a variation that under-estimates your position attracts interest, and since 1 July 2025 that interest is no longer deductible. The judgement is in matching the variation to a defensible projection of the full year. If you are unsure, pay the pre-filled amount and revisit it at Q2 with more data; the estimated payments page explains the mechanics.
6. What the ATO is matching before you press lodge
The activity statement is no longer a self-reported form the ATO reads later. Before and after lodgement it is compared against STP (wages and withholding), super fund reporting (contributions received, per employee, per payday), the taxable payments reports your customers lodge about you if you are a contractor in a reportable industry, and bank-interest and merchant-facility data. A BAS that disagrees with any of these is not wrong - but it will be asked about. Reconcile to the same sources the ATO uses and the question never comes.
7. Lodge, pay, file
Lodge through your registered BAS Agent’s portal or Online services, pay by 28 October (the agent extension to 25 November applies to lodgement and payment together, only if lodged through the agent), and keep the lodged statement, the GST audit report and the STP reconciliation together. The ATO can review a BAS for four years; the file you keep in October 2026 is the one you will want in 2030.
The ten-minute pre-flight
- All accounts reconciled to 30 September; nothing older outstanding.
- GST audit report scanned by tax code for the five traps.
- Cash versus accruals method confirmed and unchanged.
- W1 and W2 agree to STP for the quarter; award back-pay sits in the right period.
- Super reported, received and accrued are one number.
- PAYG instalment left as pre-filled, or varied on a written projection.
- Lodged, paid, filed - with the working papers.
If you want a sense-check of the number before you lodge, the BAS estimator adds up sales, purchases, PAYG withheld and the instalment in one place. And if the checklist above is the part of the quarter you least want to own, that is precisely the part of our year-round compliance service.
References: ATO - Due dates for lodging and paying your BAS, BAS agent lodgment program 2026–27, GST and PAYG withholding guidance, Payday Super payment deadlines; Fair Work Commission - Annual Wage Review 2026. Current at 16 October 2026.
This information is general in nature and does not constitute personal financial or tax advice. Please contact us to discuss your individual circumstances. Tax laws are subject to change; information on this page reflects legislation in effect as of October 2026.