Quarterly BAS Made Easy – Lodgement Guide for Sole Traders (2025-26)

If you’re a GST-registered sole trader, you’ll need to submit a Business Activity Statement (BAS) to the ATO every quarter (or monthly / annually depending on your situation). Your BAS reports GST collected and paid, along with any PAYG withholding or instalments. Lodging late can result in Failure-to-Lodge (FTL) penalties starting at $330 and increasing every 28 days.

2025-26 BAS due dates

• Q1: 1 Jul – 30 Sep 2025 → Due 28 Oct 2025
• Q2: 1 Oct – 31 Dec 2025 → Due 28 Feb 2026
• Q3: 1 Jan – 31 Mar 2026 → Due 28 Apr 2026
• Q4: 1 Apr – 30 Jun 2026 → Due 28 Jul 2026

(If you lodge through a registered BAS or tax agent, you may get an extra four weeks.)

Before you lodge - keep these basics in check

• Reconcile sales and expense records in your bookkeeping software
• Match receipts and invoices to bank transactions
• Confirm GST details are correct for sales and purchases
• Check any PAYG withholding amounts for staff or contractors

A tidy set of records means you can lodge faster and with fewer errors.

Record-keeping essentials

The ATO requires you to keep supporting records for at least five years, including:

• Sales invoices (see our compliant-invoice guide)
• Expense receipts
• Vehicle logbooks and fuel dockets if claiming car costs (retain logbook for five years from last use)
• Copies of lodged BAS statements and payment confirmations

Digital copies are fine - scans and photos are accepted. For easier storage, link your bookkeeping software to a secure cloud folder. See our home-office, car & phone deduction guide for more record-keeping tips.

Common BAS mistakes to avoid

• Reversing GST labels: GST on sales goes in 1A; GST on purchases goes in 1B
• Mismatch between cash/accrual methods: Ensure your BAS matches your bookkeeping settings
• Late payment: If you can’t pay in full, pay what you can by the due date and arrange a payment plan
• Overpaying PAYG instalments: If income drops, vary your instalment amount so you’re not paying too much up front

BAS FAQ – quick answers

Can I stay on annual GST reporting?

Only if your turnover is under $75,000 and the ATO approves it, otherwise, quarterly BAS is mandatory.

What happens if I miss the deadline?

FTL penalties start at $330 per 28 days overdue, plus interest on amounts owing.

Do side-hustle earnings count?

Yes, if you're operating under an ABN. All sales and income under the same ABN must be reported if you’re registered for GST.

Can I amend a lodged BAS?

Yes, you can revise a BAS in ATO Online Services within four years of the original lodgement.

Lodge your BAS on-time and stay compliant

Staying on top of your BAS means fewer surprises and a cleaner GST account. Keep your records in order, note the due dates in your calendar, and aim to lodge early.

New to business? Make sure you have an ABN first - apply online in five minutes.