Lodging a business activity statement (BAS) is how businesses in Australia keep their tax obligations in check during the year. A BAS tells the Australian Taxation Office (ATO) how much goods and services tax (GST) the business has collected, how much tax the business has withheld from employee wages, and what tax installments it needs to pay. Here’s what you should know to complete, lodge, and avoid common pitfalls with your BAS.

What’s in this article?

• What is a BAS statement?
  
• Who needs to lodge a BAS?
  
• What information does a BAS statement include?
  
• How to lodge a BAS statement
  
• Common mistakes when completing a BAS
  

What is a BAS statement?

A BAS is a tax reporting form that businesses in Australia submit to the ATO. The form tracks the taxes your business collects and owes over a specific period, usually monthly or quarterly.

A BAS reports on:

• GST: What you’ve collected from customers and what you can claim back as credits

• Pay-as-you-go (PAYG) withholding: The tax you’ve withheld from employee wages

• PAYG installments: Prepaid income tax based on estimated earnings

• Other taxes: Depending on your business, this could include wine equalization tax (WET), luxury car tax (LCT), or fringe benefits tax (FBT)

Who needs to lodge a BAS?

Whether your business needs to lodge a BAS depends on your tax obligations. If your annual turnover is $75,000 AUD or more ($150,000 AUD or more for nonprofits), the ATO requires you to register for GST. Once registered, you’ll need to lodge a BAS regularly—monthly, quarterly, or annually, depending on your reporting cycle. The ATO automatically sends you a BAS when it’s time to report.

What information does a BAS statement include?

What’s on your BAS depends on what taxes your business is responsible for. Most businesses will include these sections:

GST collection

This is where you break down the GST you’ve collected on sales and the GST you’ve paid on business expenses. The difference between the two is what you owe the ATO or will be refunded. For example, if you collected $1,000 AUD in GST from customers and paid $700 AUD in GST on business purchases, your BAS will show you owe $300 AUD in GST to the ATO.

Not every sale includes GST. Some sales are GST-free, including most basic food, medicines, and exports, and others are considered input-taxed sales and are exempt. The BAS has specific fields to account for these differences, so your final GST figure is accurate.

PAYG withholding

If you have employees (or make payments to contractors who agree to have tax withheld), this section is where you report how much tax you’ve taken out of their pay to remit to the government.

PAYG installments

Some businesses and self-employed individuals prepay income tax throughout the year rather than waiting for a tax bill at the end. If the ATO has put your business on a PAYG installment system, this section is where you report and pay those installments.

You can choose to use a preset installment that the ATO calculates based on your last tax return or calculate one based on your business’s income over the year. Whatever you pay now gets credited toward your end-of-year tax bill and reduces how much you’ll owe later.

Other taxes

If your business falls into specific industries or tax categories, you might see extra sections on your BAS for FBT installments, LCT, WET, or fuel tax credits. If these taxes don’t apply to your business, they won’t appear on your BAS or can be left blank.

How to lodge a BAS statement

Once your BAS is filled out, it needs to be lodged with the ATO along with any payment due. BAS due dates depend on your reporting frequency.

If you file quarterly, your due dates will be:

• October 28 for the first quarter (July–September)

• February 28 for the second quarter (October–December)

• April 28 for the third quarter (January–March)

• July 28 for the fourth quarter (April–June)

If you file monthly, your BAS is due on the 21st of the following month. For example, August BAS is due September 21. Monthly reporting is required for businesses with turnover of $20 million AUD or more.

If you file annually, your BAS is due October 31, after the end of the financial year. Annual filing is only for small businesses that voluntarily registered for GST.

If a due date falls on a weekend or public holiday, it rolls over to the next business day. Check your BAS form or ATO reminders for exact dates.

There are multiple ways to lodge BAS statements, depending on what works best for your business:

• Online: Businesses that report monthly are required to lodge their BAS online, and others do because it’s fast, secure, and sometimes comes with extra time to pay. Businesses and nonprofits can submit via the ATO’s online services for business. Sole traders with a linked ATO account can submit via myGov. If your accounting software is ATO-integrated, you can lodge there.

• Through a tax or BAS agent: A registered tax or BAS agent can lodge on your behalf. Businesses use this option for greater accuracy and reduced administrative time. If your agent lodges your BAS, they often get extended deadlines as well.

• By mail: If you receive a paper BAS form, you can fill it out and mail it to the ATO using the pre-addressed envelope provided. If you make a mistake on a paper BAS, you’ll need to use white-out for any changes.

• By phone: If you have nothing to report—meaning no sales, no GST collected, and no PAYG withholding for the period—you can lodge a “nil” BAS via the ATO’s automated phone service.

Common mistakes when completing a BAS

Even businesses that have a lot of experience lodging BAS statements can have issues. But if you know where mistakes typically happen, you can catch them before you submit. Here are the most common errors:

Incorrect GST reporting

Many BAS mistakes happen because of miscalculations or incorrect classifications in the GST section. Here’s where businesses can slip up:

• Confusing GST-inclusive vs. GST-exclusive amounts: If your numbers are inaccurate here, your totals will be wrong. Check whether figures on invoices include or exclude GST.

• Claiming GST credits incorrectly: You can claim GST credits only for purchases that included GST. If you buy from a supplier who isn’t GST-registered or the purchase is GST-free (such as food or medical services), you can’t claim a GST credit.

• Misclassifying transactions: If you treat a GST-free sale as taxable, or vice versa, your BAS figures won’t add up correctly. Double-check invoices, and use the correct tax codes in your accounting software to avoid this.

BAS form misunderstandings

As with any official form, inputting figures into the wrong section can cause problems. The BAS sections don’t always feel intuitive, especially if you’re filling out the form manually rather than using accounting software.

PAYG withholding errors

If you have employees, you’re responsible for reporting and paying tax withheld from wages. Businesses can make these mistakes:

• Forgetting to report all taxable wages: Missing an employee’s salary or contractor payment can mean underpaying tax to the ATO.

• Not matching payroll records to BAS: The amount you report on your BAS must match what’s in your payroll system. Before lodging, cross-check these figures.

Missing BAS deadlines

Late BAS lodgment can be costly, even if you don’t owe any tax for that period. Here’s why:

• The ATO can issue failure-to-lodge penalties, even for a nil BAS.

• If you owe money and lodge late, interest can accrue on overdue amounts.

Take BAS deadlines seriously. If you’re struggling to pay your BAS amount, you still need to lodge it on time. The ATO allows payment plans, but lodging late will still lead to penalties.

Poor recordkeeping

Disorganized records, including missing invoices, forgotten sales, and incorrect expense tracking, can lead to misreported figures at BAS time. Lost receipts mean you might claim GST incorrectly or miss a deduction. Unrecorded sales could result in underreporting income.

Maintaining accurate, up-to-date records will make it easier to complete your BAS and ensure you have the right documentation ready if the ATO asks for details. If necessary, consult a BAS agent or accountant for help with compliance.