How to Lodge BAS: A Step-by-Step Guide for SMEs

How to Lodge BAS: A Step-by-Step Guide for SMEs
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Lodging your BAS in Australia? Here’s what you need to know

Running a business in Australia means keeping on top of your tax obligations, and lodging your Business Activity Statements (BAS) is a big part of that. It’s not just about ticking a compliance box; getting it right helps you manage your cash flow and avoid penalties.

If BAS feels a bit overwhelming at first, you’re not alone. But once you know what’s required, it’s actually a pretty straightforward process. 

This guide walks you through how to lodge your BAS, step by step. From what to prepare, right through to hitting submit.

In this guide, we’ll break down the accounting process into simple, practical steps; no jargon. You’ll learn how your money moves, how to track it properly, and what it all means for your bottom line.

By the end, you’ll walk away with the confidence to manage your books smarter, stay compliant, and make decisions that actually move your business forward.

Need help lodging BAS?

What is a business activity statement (BAS)?

A Business Activity Statement, BAS for short; is how most Aussie businesses report and pay key taxes to the ATO. Think of it as your regular tax check-in with the tax office.

Your BAS covers things like:

  • GST collected on sales
  • GST credits from business purchases
  • PAYG withholding for employee wages
  • PAYG instalments for your own tax
  • FBT instalments, if they apply to your business

Depending on what you’re registered for, your BAS might also include things like Wine Equalisation Tax (WET) or Luxury Car Tax (LCT). The ATO tailors each BAS to suit your business, so what shows up on your form might be different to the next business.

It’s all about keeping your tax reporting aligned with your actual business activity.

What is a BAS
What is a BAS

Who needs to lodge a BAS?

If your business is registered for GST, lodging a BAS isn’t optional, it’s a legal requirement.

You’ll generally need to register for GST (and start lodging BAS) if:

  • Your business has an annual turnover of $75,000 or more
  • You’re a non-profit organisation with turnover of $150,000 or more
  • You operate in the ride-sourcing, taxi, or limousine industry—in that case, GST registration is mandatory from the first dollar earned

     

Even if your turnover is under the threshold, you can voluntarily register for GST, which can make sense if you’re regularly buying goods or services that include GST.

Registered but didn’t trade during the period? You still need to lodge a BAS, just submit a nil BAS to let the ATO know you’re up to date.

No matter your business structure, sole trader, company, partnership or trust, if you’re GST-registered, lodging BAS is part of your regular tax routine.

What you need before lodging a BAS

Getting your BAS right starts with being organised. Before you log in to the ATO portal or open up your form, make sure you’ve got all the key info ready to go.

Here’s what you’ll need:

  • Total sales and income for the reporting period (include GST if you charged it)
  • GST on purchases: Gather tax invoices and receipts for business expenses where GST was paid
  • Employee wage records, including gross wages paid and PAYG withholding amounts
  • PAYG instalment amounts, either calculated or pre-filled by the ATO
  • If you’re claiming fuel tax credits, make sure you’ve tracked eligible purchases accurately

Good record-keeping is essential. Use accounting software or solid spreadsheets to keep your invoices, receipts, and bank transactions in order. It’s not just for your BAS, it’s a legal must and helps with everything from cash flow to audits.

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BAS Form: What each section means

At first glance, the BAS form can feel overwhelming. But once you know what each section is for, it’s much easier to navigate.

Here’s what to expect in the most common sections:

GST Section

  • G1: Total sales (includes GST)
  • G2 and G3: Exported or GST-free sales
  • G10: Capital purchases
  • 1A: GST collected on sales
  • 1B: GST paid on purchases (your input tax credits)

The difference between 1A and 1B gives you the net GST, either payable to or refundable from the ATO.

PAYG Withholding (for employees)

  • W1: Gross wages paid
  • W2: Amount withheld from employees’ pay
  • W4/W5: Other amounts withheld (e.g., voluntary agreements or no ABN withholding)

PAYG Instalments (for business owners)

  • T1-T4 or Option 3: These relate to income tax instalments for sole traders or businesses. The ATO may suggest an amount based on your last return.

Optional sections Depending on your registration, you might also see fields for:

  • Fuel tax credits
  • Luxury car tax (LCT)
  • Wine equalisation tax (WET)

What are the different options for lodging BAS

When it’s time to lodge your BAS, the ATO gives you three ways to get it done. The best method depends on your business structure and how hands-on you want to be. That said, online lodging is the way to go for speed, convenience, and fewer headaches.

Lodge BAS online (recommended)

This is the fastest and most flexible option and it’s the ATO’s preferred method too.

You’ve got a few ways to lodge online:

  • ATO Online Services
    • Sole traders: Log in via myGov with your linked ABN and myGovID.
    • Businesses: Use Online Services for Business, which requires setup with myGovID and the Relationship Authorisation Manager (RAM).
  • Through your accounting software (SBR-enabled)
    If you use cloud accounting tools like Sleekbooks or XERO, you can lodge directly from your dashboard. That means no extra data entry and fewer errors.

Lodging online often gives you up to two extra weeks to lodge and pay and any refunds are processed faster.

Use a registered BAS or tax agent

Want a professional to handle it for you? No worries, registered agents can:

  • Prepare and lodge your BAS correctly
  • Help keep your records in check
  • Give you peace of mind with ATO compliance

Agents also get longer extensions than standard deadlines. You can search for a registered BAS or tax agent on the Tax Practitioners Board (TPB) register.

Lodge by mail (not recommended)

Paper forms still exist, but they’re not the go-to anymore.

  • The ATO might send you a paper BAS if you’ve never lodged electronically.
  • You fill it out by hand and post it to the ATO.
  • It’s slower, less accurate, and doesn’t come with lodgement extensions.

If you’re still lodging by mail, it might be time to switch. Online is easier, faster, and more secure.

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5 steps to lodge BAS online via the ATO portal

Lodging your BAS online is the most efficient way to meet your ATO obligations, especially if you’re a sole trader, company, or trust using myGovID. Here’s how to do it right the first time.

Step 1: Log in to ATO online services

  • Sole traders: Use your myGov account (linked to your ABN) and log in with your myGovID.

     

  • Companies, trusts & partnerships: Use Online services for business, you’ll need myGovID set up and linked via Relationship Authorisation Manager (RAM).

     

Step 2: Access Your BAS form

Once logged in:

  • Head to ‘Activity Statements’.
  • You’ll see a list of outstanding BAS forms (labelled by period end dates).
  • Click on the one you want to lodge.

     

Some fields may be pre-filled by the ATO based on past lodgements or PAYG installments. 

Step 3: Complete the required information

Use your bookkeeping software or reports to complete these sections:

  • G1: Total sales
  • 1A: GST on sales
  • 1B: GST on purchases
  • W1, W2: PAYG withholding (if you pay employees)

Double-check every figure. Accuracy matters, and mistakes can lead to penalties or delayed refunds.

Step 4: Make the declaration

Before lodging, you’ll be asked to declare that the info is true and correct to the best of your knowledge. Tick the box, then hit Submit.

Step 5: Save your confirmation

Once lodged:

  • Save the lodgement receipt or download the BAS as a PDF.
  • Keep this for your records; it’s your proof if the ATO ever follows up.

BAS due dates and lodgement cycles

Your BAS lodgement frequency depends on your business circumstances, mainly your GST turnover. Most small businesses lodge quarterly. Larger businesses (with GST turnover of $20 million or more) generally lodge monthly, while some very small businesses (voluntary GST registrants with turnover under $75k) might be eligible to lodge annually, though this is less common.

Quarterly due dates are generally the 28th day of the month following the end of the quarter (October, February, April, July). If you lodge online yourself or use a registered BAS agent or tax agent, you often get an extension of several weeks. Check the ATO website for the key lodgement and payment dates specific to your situation and lodgement method for each financial year.

It’s really important to lodge and pay on time. Failing to do so can result in penalties and interest charges from the Australian Taxation Office. If you anticipate difficulty meeting a deadline, perhaps due to unforeseen circumstances like needing emergency management support or facing mental health challenges affecting your business, contact the ATO or your agent as soon as possible, you’ll find they may offer options like a payment plan or lodgement extension.

Reporting Period

Due Date (Paper & Self-Lodgers)

Due Date (Online Self-Lodgers & Agents – Typical Extension)

 

Quarter 1: July – September

28 October

Usually extended into November

Quarter 2: October – December

28 February

Usually extended into late February/early March

Quarter 3: January – March

28 April

Usually extended into May

Quarter 4: April – June

28 July

Usually extended into August

Note that specific extension dates can vary slightly year to year and depend on the agent’s specific lodgement program. Always confirm the exact due dates with the ATO or your registered agent. If a due date falls on a weekend or public holiday, it automatically shifts to the next business day.

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How to pay your BAS (or claim a refund)

If your BAS shows that you owe money to the ATO, you’ll need to pay it by the due date. Here’s how to do it:

3 ways to pay your BAS

  • BPAY: Use the Biller Code and unique PRN (Payment Reference Number) listed on your BAS form.
  • Credit/debit card: Pay online using the ATO’s Government EasyPay system.
  • Bank transfer (EFT): Send funds directly to the ATO’s account. Use your PRN or ABN to make sure the payment is matched to your BAS.

Always double-check that your payment details are correct. Using the wrong reference could delay processing or leave your BAS marked as unpaid.

Expecting a Refund?

If your GST credits (1B) are higher than the GST you collected (1A), you might be due a refund. Lodging online usually means faster processing, expect the money in your business bank account within 12–14 business days. Just make sure your account is up to date with the ATO.

7 common mistakes to avoid when submitting your BAS

Mistakes on your BAS can lead to delays, penalties, or ATO follow-ups. Avoid these common pitfalls:

  1. Misreporting GST: Don’t claim GST on GST-free items or input-taxed sales. Check that tax invoices are valid before claiming credits.
  2. Wrong wage and PAYG figures: Double-check wages (W1) and withholding (W2) amounts, especially if you pay directors or contractors.
  3. Missing cash sales: Report all income, even if it wasn’t invoiced or went through EFTPOS.
  4. Incorrect PAYG installments: If you’re paying income tax in installments, use the correct amount—either calculated or pre-filled by the ATO.
  5. Fuel tax credit errors: Only claim what you’re entitled to, and make sure the fuel usage and business purpose are clearly documented.
  6. Simple data entry slip-ups: Watch for typos, misplaced decimals, or wrong figures—review everything before submitting.
  7. Lodging late: Set calendar reminders well before the due date and keep your records in shape. Late lodgements often mean penalties and missed refund opportunities.

Why good record-keeping makes BAS easier

Strong record-keeping is the backbone of a smooth BAS process and it’s a legal requirement.

Here’s what to keep:

  • Invoices: For both sales and purchases, showing GST details.
  • Receipts: Especially for cash expenses.
  • Bank statements: With clear transaction descriptions.
  • Payroll records: For wages, PAYG, super, and leave.

Use accounting software to keep things organized, it’ll save time and reduce risk of errors. Whether you’re calculating GST, PAYG withholding, or tracking income for fuel tax credits, good records make everything easier.

Keep records for at least five years from the date they’re created or the transaction is completed, whichever is later.

Wrapping up

Lodging your BAS doesn’t need to be overwhelming. Once you know what’s required, it becomes a regular rhythm in your business admin.

  • Know your BAS cycle and due dates
  • Keep records up to date
  • Use tools or a registered agent to stay compliant
  • Don’t leave it to the last minute

If you’re not sure whether you’re doing it right, or just want peace of mind, Sleek’s experts are here to help.

Let’s make BAS less of a burden. Get in touch today and take control of your tax reporting.

Talk to our Sydney based team today

FAQs on Lodging Your BAS

Even if no payment is due, the ATO may still apply a Failure to Lodge (FTL) penalty. Timely submission is required whether your BAS is payable or nil.

Yes. You can revise your BAS online within two years to correct mistakes. If it significantly changes your GST or PAYG obligations, interest or penalties may apply.

Only if the contractor has a voluntary withholding agreement or doesn’t provide an ABN. Otherwise, regular contractor payments aren’t reported under PAYG withholding on your BAS.

Registered BAS and tax agents typically get 4-week extensions on quarterly BAS lodgements. This gives you extra time, but you must be on the agent’s lodgement program.

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businesses worldwide.
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16,000 surveyed clients.