What is a business activity statement and who needs to lodge one?
According to the ATO’s taxation statistics, about 3.7 million active GST registrants in Australia are required to lodge Business Activity Statements. The ATO’s GST statistics also show that GST liabilities collected through BAS lodgements totalled about $79.4 billion. If you’re learning how to fill out a bas statement, that scale shows why accuracy matters.
A What is a Business Activity Statement (BAS) guide can help with the basics, but the short answer is this: a business activity statement is a form submitted to the Australian Taxation Office (ATO) so businesses can report and pay tax obligations, including Goods and Services Tax (GST), Pay As You Go (PAYG) withholding, and other levies.
If your business is registered for GST, you generally need to lodge one. This guide also covers how to complete a BAS for small business, what to gather before starting, and how to avoid errors that affect cash flow.
What taxes and obligations does a BAS cover?
A BAS can include several tax reporting areas, depending on how your business is registered. The most common are:
- GST collected on sales
- GST paid on business purchases
- PAYG withholding from employee wages
- PAYG instalments
- Fuel tax credits, if your business is eligible
- Fringe benefits tax instalments, if they apply
Not every field will apply to every business. The ATO tailors the activity statement to your registrations, so your BAS form may look shorter than another business’s form.
Which businesses are required to lodge a BAS?
Any business registered for GST must lodge a BAS. This includes sole traders, companies, partnerships, and trusts with an ABN (Australian Business Number).
Small businesses make up most BAS lodgers. The ATO’s small business tax data shows that businesses with turnover under $10 million account for the overwhelming majority of GST-registered entities.
How often do you need to lodge?
Your lodgement cycle depends on your GST turnover and ATO reporting setup:
- Monthly: Usually for larger businesses or businesses the ATO requires to report more often
- Quarterly: Common for many small businesses
- Annually: Available to some smaller GST-registered businesses
Your BAS covers a specific tax period. It’s also different from an instalment activity statement, which is generally used to report PAYG instalments or PAYG withholding when GST reporting is not required.
What information do you need before filling out a BAS?
Before you open the BAS form, you need clean financial records for the reporting period. That means reconciled accounts, accurate GST collected and paid figures, PAYG withholding amounts, and any eligible credits such as fuel tax credits. The cleaner your records are before lodgement, the less time you’ll spend fixing errors later.
Good small business bookkeeping gives you the numbers the BAS depends on. If your sales, purchases, wages, and withholding records are scattered across spreadsheets, bank feeds, and receipts, complete those checks before touching the form.
Financial records and documentation you need to gather
Start with the source records that support each BAS figure:
- Total sales for the reporting period
- GST collected on taxable sales
- GST paid on business purchases
- GST credits you intend to claim
- Total wages and salary payments
- PAYG withholding amounts
- Fuel tax credits, if applicable
- Adjustments, refunds, or corrections from previous periods
How to reconcile your accounts before lodgement
Reconciliation means checking that your records match your bank transactions, invoices, payroll reports, and accounting software. A simple process works well:
- Match sales invoices to bank deposits.
- Match supplier bills and receipts to payments.
- Check that GST has been coded correctly.
- Compare payroll totals against wage payments.
- Review any unusual transactions before entering figures.
This step is where many BAS errors are prevented.
A pre-lodgement checklist for small businesses
Before lodging, ask:
- Have all sales been included?
- Have GST-free sales been separated from taxable sales?
- Are private expenses excluded?
- Do payroll totals match your payroll software?
- Do PAYG withholding figures match employee pay records?
- Have reports been saved for audit-ready records?
Payroller helps by letting users download financial and payroll reports that feed into BAS preparation, reducing manual entry and keeping payroll data organized.
How do you fill out each section of the BAS form?
Filling out the BAS form comes down to entering the right figures into the right labelled fields. The form is split into sections for GST, PAYG withholding, PAYG instalments, and sometimes other obligations. If you’re asking, “How do I fill out a BAS statement step by step?”, start by matching each field to the records behind it.
Visual note: This is the best place for an annotated BAS form image or screenshots showing where G1, G10, G11, 1A, 1B, W1, and W2 appear.
How to complete the GST section (G1 to G20)
Use your reconciled sales and purchase records for this part of the business activity statement.
-
G1: Total sales
Enter total sales for the tax period. This includes taxable sales, GST-free sales, and input-taxed sales. Do not include GST separately if your records already show GST-inclusive sales. -
G2: Export sales
Enter export sales that are GST-free. These still form part of total sales, but they are reported separately. -
G3: Other GST-free sales
Enter other GST-free sales, such as certain food, health, education, or eligible supplies. -
G10: Capital purchases
Enter purchases of business assets, such as equipment, vehicles, or machinery. These are not everyday operating expenses. -
G11: Non-capital purchases
Enter regular business purchases, such as supplies, rent, software subscriptions, and contractor invoices. -
1A: GST on sales
This is the GST your business collected from customers. For GST-inclusive taxable sales, it is usually calculated as 1/11 of the sale amount. -
1B: GST on purchases
This is the GST you can claim back on eligible business purchases. In plain English, input tax credits are the GST credits you receive for GST paid to suppliers.
For anyone learning how to complete a BAS for small business, the main habit is simple: do not guess. Every figure should tie back to invoices, receipts, payroll records, or reports.
How to fill in PAYG withholding fields
PAYG withholding fields relate to amounts paid to employees and amounts withheld from those payments.
-
W1: Total salary, wages, and other payments
Enter total gross payments made to employees during the reporting period. This should match your payroll records. -
W2: Amount withheld from wages
Enter the tax withheld from employee wages. This is the amount you remit to the ATO.
These figures should tie directly to payroll records. Payroller helps here because gross wages and PAYG withholding are already captured through payroll processing. If you need the figures, start by downloading a report in Payroller and matching the totals to W1 and W2 before you lodge a BAS.
What to do if you have additional obligations, fringe benefits tax, fuel tax credits?
Some businesses will see extra fields on the BAS form.
-
Fringe benefits tax fields, F1 and F2
These apply when your business has fringe benefits tax instalments or related adjustments. -
Fuel tax credits, 7C and 7D
These apply if your business can claim fuel credits for eligible fuel used in business activities. -
Other ATO obligations
Your activity statement may include other fields based on your registrations.
If a field does not apply, do not enter a figure just to fill space. The BAS form is tailored to your business registrations, so focus only on the labels shown to you.
How do you lodge a BAS once it is complete?
Once your BAS is filled out and figures are verified, you can lodge it through ATO online services, myGov, a registered BAS agent, or compatible accounting software. Digital lodgement is now the normal method for Australian businesses because it reduces paper handling, creates a receipt trail, and speeds up processing.
The ATO’s annual report shows that over 70% of BAS lodgements are submitted digitally through myGov, ATO online services, or registered agents.
Lodging through ATO online services or myGov
If you lodge a BAS yourself, you can use:
- ATO online services for business
- myGov, if your business access is set up
- Online services linked through your ABN
After submission, save the lodgement receipt and payment reference details.
Lodging through a registered BAS agent
A BAS agent can lodge on your behalf. This can be useful if your records need review, your business has multiple registrations, or you want another set of eyes before lodgement.
Some registered tax agent and BAS agent arrangements may also provide access to different lodgement timelines, depending on the ATO’s agent program settings.
Using payroll or accounting software to lodge directly
Some accounting software and payroll software connect with the ATO and can reduce manual data entry. Single Touch Payroll (STP) reporting can also support the accuracy of wage and withholding records used in BAS preparation.
Before lodging, check that:
- Your sales and purchases are reconciled.
- PAYG withholding totals match payroll.
- The lodgement receipt is saved.
- Payment has been scheduled or made.
What are the most common mistakes when completing a BAS?
The most common BAS mistakes include miscalculating GST on sales and purchases, entering gross figures where a different figure is required, missing income streams, and misreporting PAYG withholding. Each error can affect what you pay or claim, and repeated errors can draw ATO attention.
The ATO’s GST gap research estimated the net GST gap at 7.3%, or $5.8 billion, with small business reporting errors forming part of the issue. That makes accurate BAS reporting more than admin, it protects cash flow and compliance.
GST calculation errors and how to avoid them
The most common mix-up is between:
- 1A: GST on sales, the GST you collected
- 1B: GST credits on purchases, the GST you can claim back
Do not offset these manually before entering them. Enter each figure in the correct field and let the BAS calculation handle the net amount.
PAYG withholding mistakes that trip up small businesses
PAYG errors often happen when payroll records do not match BAS figures. Common causes include:
- Using net wages instead of gross wages for W1
- Missing bonus, commission, or allowance payments
- Entering the wrong withheld amount at W2
- Forgetting corrections from prior pay runs
Payroll software reduces this risk by giving you a single source for gross wages and withholding.
Forgetting to include all income and expense categories
Check for income outside your usual sales process, such as cash sales, online platform income, rebates, or asset sales. On the expense side, only claim tax credits where you have valid records and the purchase relates to the business.
How to cross-check your BAS before lodging
Before submitting the activity statement:
- Compare BAS sales to your profit and loss report.
- Match GST collected to taxable sales.
- Match GST credits to supplier records.
- Compare W1 and W2 to payroll summaries.
- Check that total GST collected minus credits makes sense against cash flow.
A five-minute cross-check can prevent a time-consuming amendment.
What happens if you make an error after lodging a BAS?
If you find an error after lodging your BAS, you can amend it. The ATO allows businesses to correct some errors in the next BAS period, while other errors require a revised BAS lodgement. The right path depends on the size of the error, the tax type, and whether the correction fits the ATO’s correction rules.
When and how to lodge a BAS amendment
A BAS amendment is used when the original lodged figures need to be changed. You can generally amend through:
- ATO online services
- A registered BAS agent
- Compatible accounting software
Use the same records you relied on for the original lodgement, then identify the exact field that needs correction.
Errors you can fix in the next BAS period
The ATO allows some GST errors to be corrected in a later BAS if they meet the correction rules. A common threshold used for many small businesses is the $10,000 error value rule, but the treatment depends on the type of mistake and reporting circumstances.
Typical next-period corrections may include:
- A missed purchase invoice
- A small GST coding error
- A duplicated transaction
- A late supplier adjustment
How Payroller helps you identify discrepancies before and after lodgement
Payroller keeps payroll records in one place, which makes wage and withholding discrepancies easier to trace. If W1 or W2 looks wrong after lodgement, you can go back to payroll summaries, pay runs, and STP records to see where the figure came from.
That audit-ready trail saves time when checking whether a BAS amendment is needed.
What are the BAS lodgement deadlines and what happens if you miss one?
BAS deadlines depend on your reporting cycle. Quarterly lodgers generally have a set period after each quarter ends to lodge and pay. Monthly and annual lodgers follow different cycles. If you miss a deadline, the ATO can apply a Failure to Lodge penalty, which accrues for each 28-day period the activity statement remains outstanding.
Key lodgement dates by reporting cycle
Do not rely on saved calendar dates from old articles. BAS timing can depend on your reporting setup, lodgement channel, and whether you use an agent.
Use this process instead:
- Check your ATO account for the current due date.
- Review the ATO’s BAS due dates guidance.
- Set reminders before the tax period ends.
- Schedule review time before payment is due.
Understanding Failure to Lodge penalties
A Failure to Lodge penalty can apply when you do not lodge a BAS by the due date. The penalty amount depends on your business size and how long the lodgement remains outstanding.
Late lodgement can also affect cash flow because you may need to pay overdue tax and penalties close together.
How to request a lodgement extension from the ATO
If you need more time, contact the ATO before the deadline where possible. A BAS agent may also be able to request an extension or access agent lodgement arrangements.
Deadline alerts in software are worth using. BAS is only one part of your broader tax compliance obligations, and missed dates can create extra admin across payroll, GST, and reporting.
How does Payroller simplify the BAS preparation process?
Payroller streamlines BAS preparation by capturing payroll data, including gross wages and PAYG withholding, as part of regular pay runs. That means the figures you need for the BAS are already organized before you open the BAS form. Instead of pulling wage and withholding totals from spreadsheets, you can generate reports in a few clicks.
How Payroller captures PAYG data through Single Touch Payroll
Payroller supports Single Touch Payroll (STP), which means payroll data is recorded as part of the pay run process. For BAS preparation, this helps with:
- W1 gross wage totals
- W2 PAYG withholding totals
- Employee payment records
- Reporting consistency across pay periods
That reduces the risk of retyping or misreading payroll figures.
Generating reports in Payroller for BAS preparation
The most useful reports for BAS work include:
- Payroll summaries
- PAYG withholding reports
- Pay run records
- Employee payment details
These reports help you match payroll totals to the business activity statement and keep records ready if figures need review.
How Payroller supports BAS agents and tax professionals
For bookkeepers and BAS agents, Payroller’s multi-client dashboard helps manage payroll records across multiple businesses. That matters when preparing BAS figures for several clients at once, especially where deadlines overlap.
Payroller also supports workflows around helping clients with tax compliance by keeping payroll data accessible, structured, and aligned with BAS reporting needs.
Frequently asked questions about filling out a BAS statement?
The questions below answer common points of confusion for small businesses completing a BAS for the first time or after a change in circumstances. If you’re unsure where to start, focus first on whether you are registered for GST, which reporting cycle applies, and what the ATO has included on your BAS form.
Do I need to lodge a BAS if I have no GST to report?
Yes. If the ATO has issued a BAS, you still need to lodge it, even if there is no GST to report. This is often called a nil BAS.
Can I fill out a BAS by hand, or does it need to be done online?
Some businesses may still receive paper forms, but online lodgement is the better method for most businesses. You can use myGov, ATO online services, a BAS agent, or compatible software.
What is the difference between a BAS and an IAS?
A BAS reports GST and may also include PAYG withholding and other obligations. An instalment activity statement is generally used when a business has PAYG instalments or withholding to report but does not need to report GST.
How do I know if my BAS figures are correct before I submit?
Check your BAS form against sales reports, purchase records, payroll summaries, and bank reconciliations. Your GST, PAYG, and total sales figures should all trace back to source records.
Learning how to fill out a bas statement becomes far more manageable when the right systems are already in place. BAS preparation is a routine business process, not something that should require last-minute spreadsheets or guesswork every reporting period.
Payroller handles the payroll data side of that process, including PAYG withholding, gross wages, and STP reporting, so the numbers going into your BAS are accurate before you even open the form. That gives business owners, bookkeepers, and BAS agents a cleaner starting point and fewer manual checks.
Start your free Payroller account today and take the manual work out of BAS preparation.