Complete BAS Lodgement Guide for 2026

Business Activity Statements (BAS) are a critical part of running a business in Australia. If you're registered for GST, you need to lodge a BAS - and getting it right is essential to avoid penalties and stay compliant with the ATO.

This comprehensive guide covers everything you need to know about BAS lodgement in 2026, from understanding what's required to avoiding common mistakes.

What is a BAS?

A Business Activity Statement is a form submitted to the Australian Taxation Office (ATO) to report and pay several tax obligations, including:

• Goods and Services Tax (GST) - The GST you've collected and paid
• Pay As You Go (PAYG) Instalments - Pre-payments towards your expected income tax
• PAYG Withholding - Tax withheld from payments to employees and contractors
• Fuel Tax Credits - Credits for fuel used in business activities
• Other taxes - Wine equalisation tax, luxury car tax, etc.

Who Needs to Lodge a BAS?

You must lodge a BAS if you're registered for GST. GST registration is required when your business has an annual turnover of $75,000 or more ($150,000 for non-profit organisations).

Even if your turnover is below this threshold, you may choose to register voluntarily to claim GST credits on your business purchases.

BAS Lodgement Deadlines for 2026

BAS deadlines depend on your reporting frequency. Here are the key dates:

Quarterly BAS Deadlines

How to Calculate Your GST

There are two methods for calculating GST on your BAS:

1. Accounts Method (Recommended)

Calculate the actual GST amounts from your accounting records:

• Add up all GST collected on sales (1A)
• Add up all GST paid on purchases (1B)
• The difference is what you owe (or are owed)

2. Calculation Sheet Method

For simpler businesses, you can use the ATO's calculation worksheet to estimate GST based on total sales and purchases.

Common BAS Mistakes to Avoid

1. Missing deadlines - Late lodgement attracts penalties and interest charges
2. Incorrect GST calculations - Double-check your figures before submission
3. Claiming personal expenses - Only claim GST on genuine business purchases
4. Not keeping records - You must keep tax invoices for 5 years
5. Forgetting to lodge nil BAS - Even no activity needs to be reported
6. Mixing cash and accrual accounting - Be consistent with your reporting method

BAS Preparation Checklist

Before lodging your BAS, make sure you have:

• Reconciled all bank accounts for the period
• Categorised all transactions with correct GST codes
• Collected all tax invoices for purchases over $82.50
• Verified all sales have been recorded
• Reviewed any unusual transactions
• Checked PAYG withholding matches payroll reports

How AxiomBlue Simplifies BAS

AxiomBlue's platform is designed to make BAS preparation effortless:

• Automatic GST tracking - Every transaction is coded with the correct GST treatment
• Bank reconciliation - Keep your records up to date with automatic bank feeds
• BAS-ready reports - Generate reports that match BAS requirements exactly
• Deadline reminders - Never miss a lodgement date
• Professional review - Our BAS agents review before lodgement

Need Help?

If you're struggling with BAS or want to ensure you're maximising your claims while staying compliant, AxiomBlue can help. Our bookkeeping service includes BAS preparation and lodgement by registered BAS agents.

Learn more about our BAS services or try our demo to see how the platform works.