How to Lodge a Business Activity Statement (BAS) in Australia

If you're running a business in Australia, lodging your Business Activity Statement (BAS) is a key part of staying on the right side of the ATO. Get it wrong, and you could face penalties starting at $222 for late lodgements in 2026, plus interest charges that add up fast. Whether you're a sole trader juggling GST and PAYG or a growing enterprise with employees, this guide walks you through how to lodge a Business Activity Statement (BAS) in Australia step by step, using the latest 2026 rules.

What is a Business Activity Statement (BAS)?

A BAS is your quarterly (or monthly) report to the ATO where you declare GST collected, claim input tax credits, report PAYG withholding from employees, and pay instalments towards your income tax. It's essentially a snapshot of your business's tax obligations for the reporting period, helping the ATO keep tabs on compliance while you settle up or claim refunds.

For most Aussies in business, the BAS combines multiple taxes into one form. If you're GST-registered, it's mandatory. Even if you're not, PAYG obligations might pull you in. Think of it as your business's regular tax check-in – miss it, and the ATO notices quickly.

Who Needs to Lodge a BAS?

• GST-registered businesses: Mandatory if your annual turnover hits $75,000 or more (or $150,000 for non-profits). Voluntary registration below that still requires BAS lodgement.
• Businesses with employees: You must report PAYG withholding (tax deducted from wages).
• PAYG instalment payers: Pre-payments on your business income tax, calculated by the ATO based on prior years.
• Specific industries: Fuel tax credits, luxury car tax (LCT), or wine equalisation tax might apply.

If you're a sole trader without employees or GST, you might get an Instalment Activity Statement (IAS) instead – simpler, but still due on time.

Understanding BAS Reporting Frequencies and Due Dates for 2026

Your BAS frequency depends on turnover and ATO assessment. Most small businesses lodge quarterly, but larger ones go monthly. Due dates shift to the next business day if they fall on weekends or public holidays.

Quarterly BAS Due Dates (2025-26 Financial Year)

Standard deadlines for self-lodgers:

• Q1 (July-Sept): 28 October 2025
• Q2 (Oct-Dec): 28 January 2026
• Q3 (Jan-Mar): 28 April 2026
• Q4 (Apr-Jun): 28 July 2026

Tax agent lodgement: Often gets you until 21 days later, like 18 November 2025 for Q1 – a lifesaver for busy Aussies.

Monthly BAS Due Dates

For turnovers over $20 million or high-risk profiles: Due by the 21st of the following month (e.g., April BAS by 21 May 2026).

Annual GST Option

Voluntary GST registrants under $75,000 turnover can opt for annual reporting: Due 31 October 2026, or 28 February 2027 if no tax return is needed.

Step-by-Step Guide: How to Lodge Your BAS in Australia

Lodging is straightforward if you're prepared. The ATO prefers electronic methods, which often grant a 2-week extension. Here's your actionable checklist.

Step 1: Gather Your Records

Before touching the BAS, reconcile everything:

• Sales invoices and total GST collected (label 1A).
• Purchase invoices for input tax credits (label 1B).
• Payroll reports for PAYG withholding (labels W1-W5).
• Bank statements and accounting software exports.

Pro tip: Use SBR-enabled software like Xero or MYOB to auto-calculate figures – the ATO says 15% of BAS errors come from manual mistakes.

Step 2: Understand Key BAS Labels

The BAS form has specific fields. Focus on these common ones:

Label	What it Covers	Example
1A	GST on sales	$10,000 sales x 10% = $1,000
1B	GST credits on purchases	$5,000 purchases x 10% = $500 credit
G1/G3	Total sales/GST-free sales	All taxable + exempt sales
W2	PAYG withheld from employees	Sum from payroll
6A/6B	PAYG instalments	ATO-pre-filled amount

Full label guides are on the ATO site – double-check for LCT (1E/1F) if selling luxury cars over the threshold.

Step 3: Choose Your Lodgement Method

1. Online via ATO Business Portal: Link your myGov or AusKey. Prefills data, lodges instantly.
2. Accounting Software: Direct lodge through SBR (Standard Business Reporting) – easiest for most.
3. Tax Agent: They handle it, often with extended deadlines.
4. Paper Form: Rare, but mail if needed – no extensions.

Once lodged, pay any amount owing via BPAY, EFT, or Credit Card through the portal.

Step 4: Review, Lodge, and Pay

Recheck calculations – net GST is 1A minus 1B. Lodge before the due date printed on your BAS. If owed, pay same day to avoid the 2% failure-to-pay penalty.

What Happens if You're Late or Make a Mistake?

Can't meet the deadline? Contact the ATO ASAP for extensions or plans – don't wait for penalties. Late lodgement: $222 first time, up to $1,110 repeated. Errors? Lodge an adjustment via the portal or vary your next BAS.

Keep records for 5 years – the ATO can audit anytime.

Practical Tips to Simplify BAS Lodging

• Automate with cloud accounting – integrates with ATO for pre-fills.
• Set calendar reminders for due dates.
• Register for ATO online services early.
• Claim all eligible credits: GST on business purchases, even overseas if applicable.
• If importing, watch for deferred GST schemes.

For complex setups, a registered BAS agent saves headaches and often qualifies for extensions.

Next Steps to Nail Your BAS

Log into the ATO portal today, reconcile your books, and set up software integration. If it's overwhelming, chat with a tax agent via the ATO's register. Staying compliant keeps your business thriving without nasty surprises. Disclaimer: This guide uses 2026 info but isn't personal advice – consult a professional or the ATO for your situation.