How to Lodge a BAS in Australia: Step-by-Step Guide for Small Business

Lodging your Business Activity Statement (BAS) is one of the most important tax obligations for Australian small businesses registered for GST. This guide walks through exactly how to lodge your BAS using the ATO Business Portal, what each label means, and how to avoid common mistakes.

What is a BAS?

A BAS is a form you lodge with the ATO to report and pay:

• GST (Goods and Services Tax) collected and paid
• PAYG withholding (tax withheld from employee wages)
• PAYG instalments (income tax paid in advance)
• Fringe benefits tax (FBT) instalments (if applicable)
• Fuel tax credits (if applicable)

Who Needs to Lodge a BAS?

You must lodge a BAS if your business is registered for GST. GST registration is mandatory once your turnover exceeds $75,000 per year (or $150,000 for non-profit organisations).

BAS Lodgment Frequency

| Annual turnover | Frequency | Due dates | |----------------|-----------|-----------| | Under $20M | Quarterly | 28th of month after quarter end | | Over $20M | Monthly | 21st of following month | | By election | Monthly | 21st of following month |

Quarterly BAS quarters end: 30 September, 31 December, 31 March, 30 June.

Step-by-Step: Lodging via ATO Business Portal

Step 1: Log into ATO Online Services

Go to ato.gov.au and log into the ATO Online Services for Business (previously Business Portal). You'll need your myGovID linked to your ABN.

Step 2: Navigate to Activity Statements

From the dashboard, select "Activity statements" then "Lodge activity statement". Select the period you're lodging.

Step 3: Complete the GST Section (Labels G1–G20)

G1 — Total sales: Your total GST-inclusive sales for the period, including cash sales, invoiced sales, and any other taxable supplies.

G2 — Export sales: If you export goods or services, enter the GST-exclusive value here.

G3 — Other GST-free sales: Sales that are GST-free (e.g., fresh food, healthcare, certain financial services).

G10 — Capital purchases: GST-inclusive purchases of capital assets (equipment, vehicles, property).

G11 — Non-capital purchases: GST-inclusive purchases for running your business (supplies, operating expenses, services).

1A — GST on sales: The GST you collected on your sales (automatically calculated as G1 minus G2 and G3, multiplied by 1/11).

1B — GST on purchases: The GST credits you're claiming on G10 and G11.

Step 4: Complete PAYG Withholding (Labels W1–W4)

If you have employees, you must report:

W1 — Total salary, wages, and other payments: Total gross payments to employees and contractors (where withholding applies).

W2 — Amount withheld from salary and wages: The PAYG tax withheld from employee pay.

W4 — Amount withheld where no ABN quoted: Tax withheld from suppliers who didn't provide an ABN (47% withholding rate).

Step 5: Calculate Your Net Amount

The BAS calculates your position automatically:

• Net GST: GST on sales (1A) minus GST on purchases (1B)
• Total: Net GST plus PAYG withholding

Step 6: Lodge and Pay

Review your BAS carefully, then lodge it. Payment is due on the same date. Pay via:

• Direct debit (set up in advance)
• BPAY using the reference on your BAS
• Credit card (surcharge applies)
• ATO online via EFT

BAS Due Dates (Quarterly)

| Quarter | Period | Due date | |---------|--------|----------| | Q1 | July–September | 28 October | | Q2 | October–December | 28 February | | Q3 | January–March | 28 April | | Q4 | April–June | 28 July |

Common BAS Mistakes

1. Claiming GST on private expenses Only business expenses attract GST credits. Personal expenses claimed through the business must be excluded.

2. Forgetting to include cash sales All taxable supplies must be reported — including cash sales. Omitting cash is a significant compliance risk.

3. Missing the car expense limit For vehicles under the luxury car limit, you claim GST credits on the actual GST paid. Above the limit, GST credits are capped.

4. Not keeping tax invoices You need a valid tax invoice to claim GST credits on purchases over $82.50.

Making it Easier with Accounting Software

Manual BAS preparation from spreadsheets is time-consuming and error-prone. Accounting software makes it dramatically simpler:

• Automatic GST tracking on every transaction
• BAS labels pre-populated from your real data
• One-click lodgment via software BAS (SBR) integration
• Real-time GST liability dashboard

Finsori generates and pre-populates your BAS automatically, and connects directly to the ATO for lodgment.

Frequently Asked Questions

What if I can't pay my BAS on time? Lodge the BAS on time even if you can't pay. You can contact the ATO for a payment plan. Lodging late carries penalties separate from payment penalties.

Can I amend a BAS after lodging? Yes. You can revise a BAS within 4 years of the lodgment date. For errors under $10,000 GST, you can adjust in your next BAS.

What is a nil BAS? If you had no taxable sales or purchases for the period, you still need to lodge a nil BAS. You'll fill in zeros for all applicable labels.

Do I need to keep BAS records? Yes. Keep all supporting records for 5 years from the date you lodge or the transaction date, whichever is later.

Can my BAS agent lodge for me? Yes. A registered BAS agent can prepare and lodge on your behalf. This can extend your lodgment deadline.

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Also see: Xero Alternative Australia · Single Touch Payroll Australia Guide