Sole trader tax checklist before 31 October: BAS and tax return

By SlateAndTally · Updated 26 October 2026

If you're a sole trader lodging your own tax return, the end of October is the busy week of the year. The July–September quarterly BAS is generally due on 28 October, and individual tax returns you lodge yourself for the 2025–26 income year are due by 31 October 2026. In 2026, 31 October falls on a Saturday. When an ATO due date falls on a weekend or public holiday, you can generally lodge and pay on the next business day, but don't plan on the extra days. This checklist covers what to gather, check and lodge so you're not up at midnight hunting for receipts.

General information only, not tax advice. Due dates and rules can change and depend on your situation. Check ato.gov.au or speak to a registered tax agent.

First: are you lodging yourself or through a tax agent?

The 28 October and 31 October dates apply when you lodge yourself. If you're on a registered tax agent's client list before 31 October, you usually get a later due date for your tax return, and agents lodging BAS electronically often get extra time too. If you're behind, the single most useful thing you can do this week is contact a registered tax agent now, before the deadline.

Part 1: Quarterly BAS checklist (July–September quarter)

If you're registered for GST, or you pay PAYG instalments, you'll have a BAS for the September quarter. Before you lodge:

Reconcile your business bank account for 1 July to 30 September. Every deposit should be matched to an invoice or explained (transfers, refunds, personal money).
Total your sales (G1) including GST, and separate any GST-free sales.
Total your GST on purchases. You can only claim GST credits on business purchases where you hold a valid tax invoice, and for purchases over $82.50 (including GST) the tax invoice needs the supplier's ABN.
Check for private use. Phone, internet, car and home office costs usually need the private portion taken out before claiming GST credits.
Check your PAYG instalment amount or rate on the BAS the ATO has issued.
Lodge and pay through ATO online services via myGov, Online services for business, or your accounting software.

Our Sole Trader Tax & BAS keeps income, expenses and GST by quarter, so these totals are ready when you need them. It runs in your browser and keeps your data on your device.

Not registered for GST? Check the threshold

You must register for GST within 21 days of your business turnover reaching (or being expected to reach) $75,000 in a 12-month period. Rideshare and taxi drivers must register regardless of turnover. If your side hustle grew this year, check your rolling 12-month turnover, not just the financial year. Our guide to the GST threshold for side hustles explains how to calculate it, and the Side Hustle Income & Tax Tracker shows your running total.

Part 2: Tax return checklist (2025–26 income year)

As a sole trader you report business income in your individual tax return, along with a business schedule. Gather these before you open myTax:

Income

Total business income for 1 July 2025 to 30 June 2026, from your invoices and bank statements.
Payment summaries or income statements from any employment, available in myGov once your employer marks them "tax ready".
Interest, dividends, government payments and rental income, if any.
Payments from platforms (marketplaces, rideshare, freelance sites). The ATO receives data from many platforms, so make sure your figures match.

Expenses

Business expenses with receipts: tools, equipment, software, subscriptions, advertising, stock, insurance, accounting fees and bank fees.
Home office expenses, using either the fixed rate method (with a record of the actual hours you worked from home) or the actual cost method.
Vehicle expenses, using cents per kilometre or a logbook, with records to support your claim.
Depreciating assets you bought for the business. Small businesses may be able to immediately write off eligible assets under the instant asset write-off. Check the current threshold and rules on the ATO website before you claim.
Personal super contributions you plan to claim as a deduction. You must lodge a notice of intent with your super fund and get its acknowledgement before you lodge your tax return.

Other things to check

Your ABN details are current in the Australian Business Register.
Whether personal services income (PSI) rules apply, if most of your income comes from your own skills or effort for one client.
Private health insurance statement, and HELP debt if you have one.
PAYG instalments you paid during the year. They're credited against your tax.

Part 3: Records to keep

You generally need to keep business records for five years from when you lodge. That includes invoices, receipts, bank statements, logbooks, and the working for your home office and vehicle claims. Digital copies are fine if they're clear and complete. A simple habit: photograph receipts the day you get them and file them by quarter.

Part 4: Set aside tax from every payment

The biggest sole trader money stress isn't the paperwork. It's a tax bill with no money set aside. Once this year's return is lodged:

Open a separate tax savings account.
Move a fixed percentage of every payment you receive into it. Many sole traders use 25–30%, plus the GST portion if registered. Your accountant can suggest a figure that fits your income.
Pay BAS from that account each quarter.

The Sole Trader Tax & BAS estimates how much to set aside as income comes in. If you want the structure as a spreadsheet instead, see our sole trader spreadsheet guide.

Key sole trader dates for the rest of 2026–27

For quarterly BAS lodged yourself, the usual due dates are:

Q1 (July–September): 28 October
Q2 (October–December): 28 February
Q3 (January–March): 28 April
Q4 (April–June): 28 July

Put them in your calendar now, with a reminder two weeks before each one. Tax agents and BAS agents often have later dates for their clients. Always confirm your own dates in ATO online services.

Quick printable checklist

☐ Bank account reconciled to 30 September
☐ BAS sales, GST and PAYG instalment checked
☐ BAS lodged and paid
☐ Income for 2025–26 totalled and matched to bank statements
☐ Expenses and receipts gathered, private use removed
☐ Home office hours and vehicle records ready
☐ Super deduction notice acknowledged by your fund
☐ Tax return lodged, or registered tax agent engaged before 31 October
☐ Tax savings account set up for next year

Pairing your business tax with a household budget? The free Fortnightly Budget Mini helps you plan personal bills around irregular sole trader income, and our fortnightly budgeting guide explains the method.

Frequently asked questions

When is the September quarter BAS due?

If you lodge yourself, the July to September quarterly BAS is generally due on 28 October. Tax and BAS agents may have later dates for their clients.

When is the tax return due for sole traders who lodge themselves?

31 October 2026 for the 2025-26 income year. If you use a registered tax agent and are on their client list before 31 October, you usually get more time.

How long do sole traders need to keep records?

Generally five years from when you lodge your tax return.