Completing your BAS for GST

How to complete your BAS, correct GST errors and adjust a BAS.

Last updated 14 September 2026

These instructions explain how to complete the GST section of your business activity statement (BAS).

Each BAS is personalised to your business and is based on your GST registration details. It's important to report on the form you receive from us.

Most BAS are lodged online. By lodging online you:

can use 'Help' buttons for additional information to complete your form
may be eligible for an additional 2 weeks to lodge and pay your quarterly BAS.

If you choose to use a tax or BAS agent to help you complete and lodge your BAS, check they are registered with the Tax Practitioners BoardExternal Link.

For more information, see:

Choose a method to complete your full BAS

Depending on the method you choose to complete your BAS, you won’t need to complete all of the GST labels.

Identify your accounting basis

The amounts you report on your BAS depend on the accounting basis you use.

Instructions for completing your BAS

Use these detailed instructions to help you complete your business activity statement for GST.

Correcting GST errors

Explains when and how businesses can correct GST errors in a later business activity statement.

Making adjustments on your BAS

How to make changes to current or past BAS to increase or decrease the amount of GST to be paid.

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