BAS Lodgement Guide Australia | GST, PAYG & Due Dates

BAS lodgement is how Australian businesses submit a Business Activity Statement to report and pay obligations such as GST and PAYG. The ATO describes BAS as covering completion, lodgement, and payment of activity statement obligations including GST, PAYG withholding, and PAYG instalments (ATO - Business activity statements (BAS)).

This guide is for GST-registered sole traders and simple small businesses that want to understand the BAS workflow before lodging. It is general information only, not BAS agent or tax agent advice.

BAS lodgement checklist

Before lodging a straightforward BAS, collect:

• Sales totals for the period.
• GST collected on taxable sales.
• GST credits on eligible business purchases.
• PAYG instalment amount or rate if the ATO has issued one.
• PAYG withholding totals if you employ staff or have other withholding obligations.
• Records that support the amounts, including invoices and payment records.

Use the BAS calculator to check the GST section before lodging. It does not lodge for you and it does not cover every possible BAS label.

What BAS labels mean

The exact fields on a BAS depend on the business and the ATO statement issued. For many small businesses, these labels are the starting point:

The ATO BAS overview links the GST labels and PAYG withholding labels into separate BAS guidance areas (ATO - Business activity statements (BAS)). If your BAS includes fields outside this table, check the ATO instructions or ask your adviser before lodging.

GST section: G1, 1A, and 1B

The GST section is the easiest part to pre-check with a calculator.

G1 is total sales for the period. This can include more than just taxable sales, so do not assume every dollar at G1 has 10% GST attached.

1A is GST on sales. This is the GST collected from taxable supplies.

1B is GST on purchases. This is the GST credit claimed on eligible business purchases.

The BAS calculator estimates the net GST result by comparing 1A and 1B. If 1A is higher than 1B, GST is payable. If 1B is higher than 1A, the GST section shows a refund estimate.

Reporting method: cash or accrual

The timing of GST depends on the reporting method you use. The ATO GST reporting options source distinguishes reporting and payment options, including cash and accrual-style timing rules (ATO — GST reporting options).

In plain English:

• Cash basis follows when money is received or paid.
• Accrual basis follows invoice timing, even if cash moves later.

The calculator can work with either method because you enter the totals for the period. The important part is to use the same basis that matches your ATO registration and business records.

BAS due dates

The due date shown by the ATO is the date that matters for your business. For quarterly BAS, common due dates are:

The ATO BAS due dates page should be checked for the due date that applies to your statement, especially if you lodge through a tax or BAS agent or the date falls near a weekend or public holiday (ATO — BAS due dates).

PAYG fields on BAS

BAS can include PAYG fields, but there are two different PAYG concepts.

PAYG instalments are income-tax prepayments. They usually appear because the ATO has entered the business or individual into the instalment system.

PAYG withholding applies when you withhold tax from employee wages or other covered payments. Business.gov.au explains that employers collect PAYG withholding from employees and certain other workers or businesses in specific cases (Business.gov.au - Income tax for business).

If you are checking employee withholding, use the PAYG tax table guide and the pay-cycle pages for weekly tax and fortnightly tax.

Common BAS lodgement mistakes

Watch for these before submitting:

1. Treating GST-free sales as if they all include GST.
2. Claiming GST credits without a valid tax invoice or creditable purpose.
3. Mixing cash-basis and accrual-basis totals in the same period.
4. Forgetting that PAYG instalments and PAYG withholding are different.
5. Copying invoice totals into BAS without reconciling bank receipts and expenses.

If something does not reconcile, pause before lodging. A quick calculator check is useful, but it cannot decide whether a supply is taxable, GST-free, input-taxed, or outside scope.

Suggested workflow

Use this order for a straightforward quarterly BAS check:

1. Reconcile bank and invoice records for the quarter.
2. Confirm whether your figures are cash-basis or accrual-basis.
3. Use the GST calculator for individual invoice checks.
4. Use the BAS calculator for the BAS-period GST result.
5. Check PAYG fields against the ATO statement and payroll records if they apply.
6. Lodge through the ATO or your registered agent.

Related tools

• BAS calculator - estimate net GST payable or refundable.
• GST calculator - add or remove 10% GST from amounts.
• Business tax Australia guide - understand GST, BAS, PAYG, and income tax in one place.
• Sole trader tax calculator - estimate annual income tax and PAYG instalments for ABN income.