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Q4 BAS Lodgement Guide FY2026: Due Dates, GST & PAYG Checklist

Written by admin | Aug 10, 2026, 11:00:00 PM

The June quarter Business Activity Statement is often the trickiest one of the year to get right. It doesn't just report three months of GST and PAYG withholding, it also lines up with the end of the financial year, which means any errors here have a habit of flowing straight into your annual tax return.

Getting your Q4 FY2026 BAS right matters more than most business owners realise. It's not just a compliance box to tick, it's also one of the clearest signals of how accurately your books have been kept all year.

At a glance

  • The Q4 FY2026 BAS covers April, May and June 2026
  • If you lodge through a registered tax or BAS agent, the due date is 25 August 2026; self-lodged BAS statements are due 28 July 2026
  • GST reporting and PAYG withholding are the two biggest components for most businesses
  • Year-end timing makes this quarter's BAS more prone to errors than others
  • Common mistakes include incorrect GST classification, mismatched figures and late or missing adjustments
  • A clean Q4 BAS makes your annual tax return significantly easier to prepare

What's included in the Q4 BAS

Your quarterly BAS brings together several reporting obligations into one lodgement. For most small and medium businesses, this includes:

  • GST collected and paid on sales and purchases during April, May and June
  • PAYG withholding on employee wages and salaries
  • PAYG instalments, if your business pays tax by instalment rather than in one lump sum
  • Fringe benefits tax instalments, where applicable
  • Fuel tax credits, for businesses that claim them

Because this quarter also marks the end of the financial year, it's the point where any discrepancies between your BAS figures and your annual accounts tend to surface. Getting the numbers right now saves a lot of reconciliation work later.

GST: getting the reporting right

GST is usually the largest single component of a BAS, and it's also where most errors occur. A few areas worth paying close attention to for the June quarter:

  • GST-free and input-taxed sales – make sure these are coded correctly and not accidentally included in your GST collected figure
  • Capital purchases – large asset purchases made in the quarter should be reported separately from general expenses
  • Bad debts – if you've written off any unpaid invoices, you may be entitled to a GST adjustment
  • Private use apportionment – for expenses with a mix of business and private use, only the business portion should be claimed

Reconciling your GST clearing account against your BAS figures before lodging is one of the simplest ways to catch errors before they become a problem.

PAYG withholding: closing out the year correctly

PAYG withholding for Q4 should reconcile closely with your Single Touch Payroll data for the same period, since both are reporting the same wage and withholding figures to the ATO.

Before lodging, it's worth checking:

  • Withholding amounts match your payroll software exactly, not just approximately
  • Any bonuses or termination payments made in the quarter have been withheld correctly
  • Contractor payments haven't been incorrectly included in, or excluded from, withholding calculations
  • STP finalisation is completed accurately, since this data feeds directly into your employees' income statements

Discrepancies between PAYG withholding reported on your BAS and your STP data are one of the more common triggers for ATO follow-up, so it's worth resolving any gaps before you lodge.

Common preparation mistakes

Even experienced business owners run into the same handful of issues each quarter. Watch out for:

  • Coding errors in accounting software, particularly GST-free items marked as taxable or vice versa
  • Missing or duplicate transactions, often from bank feeds that haven't been fully reconciled
  • Using cash figures instead of accrual figures, or mixing the two inconsistently across the year
  • Forgetting adjustments, such as bad debts, asset sales or private use apportionment
  • Leaving reconciliation until the last minute, which leaves little time to fix errors before the deadline
  • Not separating capital and non-capital purchases, which affects how they're reported on the BAS

Most of these mistakes stem from the same root cause: reconciliation happening too late, or not at all, before the BAS is prepared. A monthly reconciliation habit throughout the year makes the Q4 lodgement significantly smoother.

Why this quarter deserves extra attention

Because Q4 sits at the intersection of quarterly compliance and annual reporting, errors here don't stay contained to a single BAS. They tend to carry through into your year-end financial statements and, in some cases, your income tax return.

Taking the time to reconcile properly this quarter isn't just about meeting the 25 August deadline, it's about starting the new financial year with accurate, reliable numbers.

Frequently Asked Questions

1. When is the Q4 FY2026 BAS due? If you lodge through a registered tax or BAS agent, the due date is 25 August 2026. If you lodge your BAS yourself, the standard due date is 28 July 2026.

2. What period does the Q4 BAS cover? April, May and June 2026, the final quarter of the 2025–26 financial year.

3. Can I fix an error after my BAS has been lodged? Yes. Most errors can be corrected by lodging a revision or including an adjustment on your next BAS, depending on the size of the error and how much time has passed.

4. Why does my BAS need to match my annual accounts? Discrepancies between BAS figures and annual financial statements can trigger ATO review, and they also make it harder to prepare an accurate tax return.

5. Should I reconcile monthly even though BAS is quarterly? Yes. Monthly reconciliation catches errors early and makes quarterly BAS preparation far quicker and more accurate.

Final thoughts

The June quarter BAS carries a bit more weight than the others, simply because of where it sits in the financial year calendar. A careful approach to GST and PAYG withholding, combined with good reconciliation habits, makes this lodgement, and the tax return that follows it, considerably easier to get right.

Talk to Rubiix

Need help preparing your Q4 BAS or reviewing your GST and payroll reporting before lodgement? Get in touch with the Rubiix team or explore our taxation services to find out how we can help.

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