Business Activity Statements: A Plain-English Walkthrough

A business activity statement looks intimidating the first time: a form full of labels and codes that seem to assume you already know what they mean. In practice, most small businesses only fill in a handful of sections, and each one asks a simple question about money you collected or withheld on the ATO's behalf.

Who has to lodge a BAS

If your business is registered for GST, you generally lodge a BAS. You may also receive one if you withhold tax from payments to employees or others, or if the ATO has entered you into PAYG instalments. The ATO issues the statement for each reporting period, and it shows only the sections relevant to you.

The ATO's business section at ato.gov.au/businesses-and-organisations covers activity statements, due dates and lodgment options in detail.

The GST section

This is the heart of most small business statements. The key labels are:

• G1, total sales. Your total sales for the period, generally including GST, depending on how you account.
• 1A, GST on sales. The GST you collected or need to account for on taxable sales.
• 1B, GST on purchases. The GST credits you can claim on business purchases, supported by valid tax invoices where required.

If 1A is larger than 1B, you pay the difference. If 1B is larger, you are due a refund. Businesses using full reporting also complete extra labels breaking down export, GST-free and capital purchases; small businesses using simpler BAS generally report only G1, 1A and 1B. Eligibility for simpler BAS depends on GST turnover; check the ATO's current threshold.

Whether you report on a cash or accrual basis matters. On a cash basis, you report GST when you are paid or when you pay. On an accrual basis, you report when you issue or receive an invoice. Eligibility for cash accounting depends on your turnover and circumstances.

PAYG withholding

If you employ staff, you withhold tax from their wages and pass it to the ATO. On the BAS, the main labels are W1, total salary and wages, and W2, the amount withheld from them. There are other labels for amounts withheld from other payments, such as payments to suppliers who don't quote an ABN.

Withheld tax is held in trust for your employees, in effect. It is one of the debts the ATO treats most seriously, and company directors can become personally liable for unpaid amounts in some cases.

PAYG instalments

PAYG instalments are prepayments towards the income tax on your business and investment income. If the ATO has entered you into the system, your BAS will include an instalment section. Depending on the option you use, you either pay an amount the ATO calculated, or apply an instalment rate to your instalment income for the period.

You can vary an instalment if you expect your income to be lower, but the variation needs to be reasonable. The ATO explains the options and the consequences of varying too low on its PAYG instalments pages.

A BAS doesn't measure how well your business did. It reports money you held for the government: GST from customers, tax from employees' pay, and your own tax paid in advance.

Reporting cycles compared

Due dates vary by cycle and by whether you lodge yourself or through an agent. The ATO publishes the current dates; registered tax and BAS agents may have access to extended dates.

How to lodge and pay

You can lodge online through the ATO's online services for business, through myGov for sole traders in many cases, through compatible accounting software, or through a registered tax or BAS agent. Paper lodgment is possible but slower. Every statement must be lodged, even if you have nothing to report for the period, unless the ATO tells you otherwise.

Payment uses the payment reference number linked to your account. If you can't pay on time, lodge anyway and contact the ATO about a payment plan. Failing to lodge creates a separate problem from failing to pay.

A quarterly BAS routine for a one-person business

Here is a practical rhythm for a sole trader registered for GST, with no employees, lodging quarterly:

1. Weekly: record every sale and purchase in your bookkeeping software or spreadsheet, attach the invoice or receipt, and transfer the GST portion of your takings into a separate holding account.
2. At quarter end: reconcile your bookkeeping to your bank statements so every transaction is accounted for once and only once.
3. Check purchases: confirm each GST credit you claim is for a business purchase, includes GST, and is supported by a valid tax invoice where required.
4. Prepare the figures: total sales for G1, GST on sales for 1A, GST credits for 1B, plus any PAYG instalment shown on the statement.
5. Review before lodging: compare with the previous quarter. A sudden jump or drop is either a real change in your business or a sign something was missed.
6. Lodge and pay by the due date, using the money already set aside.

Done this way, the BAS becomes a short review session rather than a weekend of reconstructing receipts.

Common BAS errors and how to avoid them

1. Claiming GST credits without a valid tax invoice. Keep invoices that meet the ATO's requirements.
2. Claiming credits on GST-free purchases. Bank fees, many foods and some imports don't include GST.
3. Mixing private and business purchases. Only the business portion of a purchase gives rise to a credit.
4. Spending the GST. Moving GST collected into a separate account each week prevents a cash crunch.
5. Reconciling at the last minute. Bookkeeping weekly makes the BAS a review rather than a reconstruction.
6. Ignoring corrections. Mistakes in an earlier BAS can often be corrected in a later one within limits; the ATO explains when a revision is needed instead.

Frequently asked questions

Do I need a BAS agent?

No, many small businesses lodge their own. A registered BAS or tax agent can help if your affairs are complex or you prefer to hand it over. Only registered agents can charge a fee for BAS services; check the register at tpb.gov.au.

What is an instalment activity statement?

Some people who aren't registered for GST but pay PAYG instalments, or withhold tax, receive an instalment activity statement instead of a BAS. It covers just those obligations.

What if my business had no sales this quarter?

You generally still need to lodge, reporting zero where appropriate. Lodging a nil statement on time avoids penalties for failing to lodge.