BAS Lodgement Guide
How to prepare, lodge, and pay your Business Activity Statement — with 2025-26 due dates, Simpler BAS labels explained, lodgement methods, payment options, and what happens if you lodge late.
In this guide
- 1. What is a BAS?
- 2. Who needs to lodge
- 3. Simpler BAS: the 3 fields you need
- 4. Full BAS & PAYG labels
- 5. Pre-lodgement checklist
- 6. Due dates (2025-26)
- 7. How to lodge your BAS
- 8. Worked example: quarterly BAS
- 9. Payment options
- 10. Late lodgement penalties
- 11. Correcting BAS mistakes
- 12. Common BAS mistakes
- 13. Record-keeping requirements
- 14. GST instalment method
- 15. FAQs
BAS lodgement — at a glance
- What: A form you lodge with the ATO to report GST, PAYG withholding, and other tax obligations
- Who: Every business registered for GST (mandatory if turnover ≥ $75,000)
- How often: Quarterly (most small businesses), monthly ($20M+ turnover), or annually
- Simpler BAS fields: G1 (total sales), 1A (GST on sales), 1B (GST on purchases)
- Net GST: 1A − 1B — positive means you owe the ATO; negative means refund
- Late penalty: $313 per 28-day period overdue, up to $1,565 max per BAS
- Record keeping: Keep all GST records for at least 5 years
What is a BAS?
A Business Activity Statement (BAS) is the form Australian businesses use to report and pay tax obligations to the ATO. It consolidates several tax types into a single lodgement:
- GST — how much GST you collected on sales and how much you paid on purchases (your input tax credits)
- PAYG withholding — tax you withheld from employee wages, director fees, or payments to contractors who didn't quote an ABN
- PAYG instalments — prepayments towards your expected income tax liability (if the ATO has included you in the PAYG instalment system)
- Other taxes — Wine Equalisation Tax (WET), Luxury Car Tax (LCT), and Fuel Tax Credits, if applicable
The ATO issues you a BAS notice each reporting period with a unique Payment Reference Number (PRN). You fill in the relevant labels, lodge, and pay any amount owing by the due date. If your GST credits exceed the GST collected, the ATO refunds the difference.
Who needs to lodge a BAS
You need to lodge a BAS if your business is registered for any of the following:
GST-registered businesses
Mandatory if annual GST turnover is $75,000+ ($150,000 for non-profits). Also mandatory for taxi/ride-sharing services regardless of turnover.
Voluntary GST registration
If you chose to register for GST with turnover below $75,000, you must lodge a BAS — you can't opt out of lodgement while remaining registered.
Employers (PAYG withholding)
If you withhold tax from employee wages, you report and pay the withheld amounts through your BAS. This applies even if you're not GST-registered.
PAYG instalment payers
If the ATO has placed you in the PAYG instalment system (prepayments towards your income tax), those amounts are reported on your BAS.
Nil BAS
Even if you had no sales or purchases in a period, you must still lodge a “nil BAS” with zeros in each field. Failing to lodge a nil BAS can trigger the same late-lodgement penalties as a BAS with amounts owing.
ATO Reference
Business activity statements (BAS)
ATO overview of BAS obligations, reporting options, and key dates.
View on ATO websiteSimpler BAS: the 3 GST fields you need
Since 1 July 2017, small businesses with GST turnover under $10 million use Simpler BAS by default. Instead of completing seven GST labels, you only fill in three:
Total sales
All your sales for the period — taxable, GST-free, and input-taxed. Use the GST-exclusive amount if you report on accrual basis, or the amount received if you use cash basis.
Example: You sold $55,000 worth of services this quarter (ex GST). Enter $55,000.
GST on sales
The total GST you collected on your taxable sales during the period. For most businesses, this is your taxable sales divided by 11 (or multiplied by 10%).
Example: Your taxable sales were $55,000 ex GST. GST collected = $55,000 ÷ 10 = $5,500. Enter $5,500.
GST on purchases
The total GST included in your creditable business purchases (your input tax credits). Only include GST on purchases that are for a creditable business purpose and where you hold a valid tax invoice for amounts over $82.50 inc GST.
Example: You spent $22,000 (inc GST) on business expenses. GST credits = $22,000 ÷ 11 = $2,000. Enter $2,000.
Net GST = 1A (GST on sales) − 1B (GST on purchases)
Positive result → you owe the ATO. Negative result → the ATO owes you a refund.
Try it yourself
Enter your quarterly sales and purchases to see your G1, 1A, 1B figures and net GST instantly.
Try the BAS EstimatorFull BAS & PAYG withholding labels
Businesses with GST turnover of $10 million or more must use full BAS reporting, which includes four additional GST labels on top of the Simpler BAS fields:
Additional GST labels (full BAS only)
| Label | Name |
|---|---|
G2 | Export sales |
G3 | Other GST-free sales |
G10 | Capital purchases |
G11 | Non-capital purchases |
PAYG withholding labels
If you have employees or withhold tax from other payments, you also complete the W (withholding) labels:
| Label | Name |
|---|---|
W1 | Total salary, wages & other payments |
W2 | Amount withheld from W1 |
W3 | Other amounts withheld |
W4 | Amount withheld from W3 |
ATO Reference
PAYG withholding on your BAS
How to report amounts withheld from employee wages and other payments on your BAS.
View on ATO websitePre-lodgement checklist
Run through this checklist before you lodge each BAS. It covers the steps that catch the most common errors.
Reconcile your bank accounts
Make sure every transaction for the quarter is categorised in your accounting software or records. Reconcile your bank statement balance with your books.
Check all sales are recorded
Cross-reference your invoices with your bank deposits. Look for cash sales, manual invoices, or payment platform receipts (Stripe, Square, PayPal) that may not have been auto-imported.
Review purchase classifications
Ensure each expense is coded to the correct GST category: taxable (GST applies), GST-free (no GST to claim), or input-taxed (no GST credit). Common traps: bank fees are input-taxed, not GST-free.
Verify you hold valid tax invoices
For any GST credit claim over $82.50 (inc GST), you need a valid tax invoice. Check that invoices show the supplier's ABN, GST amount, and date of issue.
Separate business and personal expenses
If you've mixed personal expenses into your business accounts, remove them. For mixed-use assets (e.g. a car used 70% for business), only claim the business portion of the GST.
Check your reporting method
Confirm whether you're on cash or accrual basis. Cash = report GST when money changes hands. Accrual = report GST when you issue or receive the invoice.
Sense-check your figures
Does G1 (total sales) roughly match your bank deposits? Is 1A approximately one-eleventh of your taxable sales? Does the net GST amount look reasonable compared to last quarter?
What this means for you
For a business with $200,000 annual turnover (all taxable, quarterly BAS)
~$4,545 net GST per quarter
That's roughly $18,182 in GST collected per year, minus your input tax credits. If your business purchases are around $80,000 (inc GST), your actual quarterly payment to the ATO would be closer to $2,727.
BAS due dates — 2025-26 financial year
Quarterly BAS deadlines
These are the standard deadlines for self-lodgement and the extended deadlines available through a registered tax or BAS agent. Electronic lodgement may qualify you for an automatic 2-week extension on Q1, Q3, and Q4.
| Quarter | Period | Self-lodge |
|---|---|---|
Q1 | Jul – Sep 2025 | 28 Oct 2025 |
Q2 | Oct – Dec 2025 | 28 Feb 2026 |
Q3 | Jan – Mar 2026 | 28 Apr 2026 |
Q4 | Apr – Jun 2026 | 28 Jul 2026 |
Q2 already includes a one-month extension (28 Feb instead of 28 Jan), so no additional electronic lodgement extension or agent concession applies.
Monthly BAS deadlines
If you lodge monthly (mandatory for businesses with GST turnover ≥ $20 million), BAS is due on the 21st of the following month. No agent concession applies to monthly lodgements.
| Reporting month | Due date |
|---|---|
| July 2025 | 21 Aug 2025 |
| August 2025 | 21 Sep 2025 |
| September 2025 | 21 Oct 2025 |
| October 2025 | 21 Nov 2025 |
| November 2025 | 21 Dec 2025 |
| December 2025 | 21 Jan 2026 |
| January 2026 | 21 Feb 2026 |
| February 2026 | 21 Mar 2026 |
| March 2026 | 21 Apr 2026 |
| April 2026 | 21 May 2026 |
| May 2026 | 21 Jun 2026 |
| June 2026 | 21 Jul 2026 |
Annual BAS
If you report GST annually or use the GST instalment method, your annual GST return for the 2025-26 financial year is due by 31 October 2026 (or 28 February 2027 if you don't need to lodge an income tax return).
ATO Reference
Due dates for lodging and paying your BAS
The ATO's official BAS due dates, including quarterly, monthly, and annual deadlines.
View on ATO websiteHow to lodge your BAS
There are four ways to lodge. All electronic methods qualify for the automatic 2-week extension on most quarters.
ATO Online Services for Business
Log in with your myGovID (not myGov) at the ATO Business Portal. Navigate to Lodgments → Activity Statements, select the period, enter your figures, and submit.
myGov (sole traders)
If you're a sole trader, you can lodge through your linked myGov account under ATO Online Services for Individuals. The process is similar to the business portal.
Accounting software (SBR-enabled)
Xero, MYOB, QuickBooks Online, and other SBR-enabled software can lodge directly to the ATO. Your transaction data populates the GST fields automatically — you review and submit from within the software.
Registered tax or BAS agent
Engage a registered BAS agent or tax agent to prepare and lodge on your behalf. Agents have access to the ATO's agent portal and may have later lodgement deadlines for most quarters.
Paper BAS
Paper lodgement is being phased out. If you still receive a paper BAS, you can post it to the ATO, but you won't qualify for the 2-week electronic extension and processing takes longer. The ATO strongly encourages switching to electronic lodgement.
ATO Reference
How to lodge your BAS
ATO guide to the different lodgement methods available for your BAS.
View on ATO websiteWorked example: preparing a quarterly BAS
Here's how a small consulting business would prepare their Q3 (January–March 2026) BAS using Simpler BAS reporting on accrual basis.
Scenario: Digital marketing consultancy
Sarah runs a digital marketing consultancy. She's GST-registered, lodges quarterly, and uses Simpler BAS on accrual basis. In Q3 (Jan–Mar 2026), her records show:
- Invoiced $66,000 (inc GST) in consulting fees — all taxable sales
- Received $1,800 in referral commissions — GST-free (under the threshold)
- Business purchases: $16,500 (inc GST) on software, contractors, and office rent
- Personal expense accidentally on business card: $220 (removed before lodging)
Step 1: Calculate G1 (total sales)
G1 includes all sales — taxable and GST-free. On accrual basis, use the GST-exclusive amounts.
| Consulting fees: $66,000 ÷ 1.1 (ex GST) | $60,000 |
| Referral commissions (GST-free, already ex GST) | $1,800 |
| G1 — Total sales | $61,800 |
Step 2: Calculate 1A (GST on sales)
Only taxable sales generate GST. The referral commissions are GST-free, so no GST on those.
| GST on consulting: $66,000 ÷ 11 | $6,000 |
| 1A — GST on sales | $6,000 |
Step 3: Calculate 1B (GST on purchases)
Only include GST on creditable business purchases. The $220 personal expense was removed. Bank fees ($55 in the quarter) are input-taxed — no GST to claim.
| GST on business purchases: $16,500 ÷ 11 | $1,500 |
| 1B — GST on purchases | $1,500 |
Step 4: Net GST
| 1A − 1B | $6,000 − $1,500 |
| Net GST payable to ATO | $4,500 |
Sarah owes $4,500 to the ATO for Q3. She lodges via Xero (SBR-enabled software) and pays by BPAY using the PRN from her BAS notice. The self-lodge deadline is 28 April 2026, but her electronic lodgement gives her until 12 May 2026.
Try it yourself
Run this scenario through the BAS Estimator — enter $61,800 at G1, $6,000 at 1A, and $1,500 at 1B.
Try this in the BAS EstimatorPayment options
You need to both lodge and pay by the due date. Lodging on time but paying late still incurs the General Interest Charge (GIC) on the outstanding amount. Here are the payment methods available:
| Method | How it works |
|---|---|
| BPAY | Pay through your bank's online banking. ATO Biller Code: 75556. Use the PRN (Payment Reference Number) from your BAS notice. |
| Direct debit | Set up automatic deduction from your bank account through ATO Online Services. Can be one-off or recurring. |
| Direct credit (bank transfer) | Transfer to the ATO's bank account using your PRN as the reference. BSB and account details are on your BAS notice. |
| Credit/debit card | Pay via ATO Online Services or Government EasyPay. Accepts Visa, Mastercard, and American Express. |
Payment plans
If you can't pay the full amount by the due date, contact the ATO before the due date to set up a payment plan. You can arrange this online through ATO Online Services, by phone (13 28 66), or through your tax agent. The GIC still applies to the outstanding balance, but you won't face additional penalties for non-payment as long as you stick to the agreed plan.
Setting aside GST throughout the quarter
A common approach is to transfer your estimated GST into a separate bank account each time you receive payment. A simple rule: move 10% of every payment received (or 1/11th of the GST-inclusive amount) into a “GST holding” account. When BAS time comes, the money is already set aside.
Late lodgement penalties
The ATO takes BAS lodgement seriously. Even if you owe nothing, failing to lodge on time triggers a Failure to Lodge (FTL) penalty. The penalty is calculated in penalty units and scales with how late you are:
| How late | Penalty units | Amount |
|---|---|---|
| 1 – 28 days late | 1 penalty unit | $313 |
| 29 – 56 days late | 2 penalty units | $626 |
| 57 – 84 days late | 3 penalty units | $939 |
| 85 – 112 days late | 4 penalty units | $1,252 |
| 113+ days late | 5 penalty units (max) | $1,565 |
One penalty unit = $313 (current as of 2025-26). Penalties are per BAS — if you have two overdue BAS lodgements, penalties apply separately to each one. The amounts above are for small entities; medium and large entities face higher multiples.
General Interest Charge (GIC)
On top of the FTL penalty, the ATO charges the General Interest Charge on any unpaid tax amount. The GIC rate is currently approximately 11.17% per annum, compounding daily. It applies from the original due date until you pay in full.
GIC deductibility change from 1 July 2025
GIC incurred from 1 July 2025 onwards is no longer tax-deductible. Previously, businesses could claim GIC as a deduction. This change makes late payment even more costly — the effective after-tax cost of GIC has increased significantly.
What this means for you
For a BAS that's 3 months overdue with $5,000 owing
$939 FTL penalty + ~$140 GIC = ~$1,079 in penalties and interest
The FTL penalty alone is 3 penalty units ($313 × 3). The GIC adds approximately $140 on a $5,000 debt over 3 months at 11.17% compounding daily. From 1 July 2025, the GIC portion is no longer tax-deductible.
ATO Reference
Failure to lodge on time penalty
ATO guidance on how failure-to-lodge penalties are calculated, when they apply, and how to request remission.
View on ATO websiteCorrecting BAS mistakes
If you find an error after you've lodged, you have two options depending on the size and type of error:
Correct on your next BAS
For most GST and fuel tax credit errors, you can adjust the figures on your next BAS instead of revising the original. This is the simpler option and avoids lodging a formal revision.
Requirements:
- The net error must be within the correction limits for your turnover
- You must correct it within 4 years of the original lodgement
- The error was not fraudulent or deliberate
Revise the original BAS
For errors that exceed the correction limits, or non-GST errors (like PAYG withholding), you need to lodge a formal revision of the original BAS.
How to revise:
- Through ATO Online Services for Business
- Through your accounting software (if it supports revisions)
- Through your registered tax or BAS agent
Voluntary disclosure reduces penalties
If you voluntarily correct a BAS error before the ATO discovers it, you generally won't face penalties for the mistake. The ATO takes a significantly more favourable view of businesses that self-correct compared to those where errors are found during an audit.
ATO Reference
Fixing BAS mistakes or making adjustments
ATO guidance on correcting errors on your next BAS vs revising a previously lodged BAS.
View on ATO websiteCommon BAS mistakes to avoid
These are the errors the ATO sees most often — and the ones most likely to trigger a review or adjustment notice.
1. Reporting GST-inclusive amounts at G1 instead of GST-exclusive
G1 (total sales) should be the GST-exclusive amount if you're on accrual basis. Including GST in this figure inflates your total sales and can trigger ATO review. If you're on cash basis, G1 is the total amount received (which may include GST).
Impact: Overstated sales, potentially higher PAYG instalments
2. Claiming GST credits on input-taxed purchases
You cannot claim GST credits on purchases related to making input-taxed supplies (e.g. residential rent, most financial services). Bank fees, loan interest, and share trading costs are input-taxed — there is no GST to claim.
Impact: Overclaimed credits, ATO adjustment + potential penalty
3. Missing GST on asset sales
If you claimed a GST credit when you bought a business asset (vehicle, equipment, fit-out), you must charge GST when you sell it. The GST is 1/11th of the sale price. This catches many businesses selling old equipment or vehicles.
Impact: Understated GST on sales
4. Lodging for the wrong period
Accidentally entering figures from the wrong quarter, or including a transaction in the wrong period based on your reporting method (cash vs accrual). On cash basis, a March invoice paid in April belongs in the April-June quarter.
Impact: Incorrect period allocation, potential ATO queries
5. Forgetting to include cash sales
Cash and EFTPOS sales that bypass your invoicing system still need to be reported. If you use a point-of-sale system, reconcile its totals with your BAS figures.
Impact: Understated sales and GST collected
6. Not apportioning mixed-use purchases
A laptop used 60% for business and 40% personal means you can only claim 60% of the GST credit. The ATO expects reasonable apportionment for any asset or expense with personal use.
Impact: Overclaimed credits
Input Tax Credit Checker
Not sure if you can claim GST on a purchase? Use the decision-tree tool to check eligibility.
Record-keeping requirements
The ATO requires you to keep all records that support the amounts on your BAS for at least 5 years. If you can't produce records to support a claim, the ATO can adjust or deny it.
What to keep
- Tax invoices for all sales and purchases
- Bank statements and merchant account records
- Receipts for business expenses (digital copies are fine)
- BAS lodgement confirmations
- Wage records, payment summaries, and PAYG withholding records
- Records of any adjustments, apportionments, or GST corrections
- Motor vehicle logbooks (if claiming GST credits on vehicle expenses)
Digital records are acceptable
The ATO accepts digital records — scanned receipts, PDF invoices, accounting software exports, and bank feeds all count. You don't need paper originals. The key requirement is that records must be readable and reproducible in their original form.
The 5-year clock
The 5-year retention period starts from the later of: when you prepared or obtained the record, or when the transaction was completed. For BAS records, this typically means 5 years from the lodgement date of the BAS that included the transaction.
ATO Reference
GST records
Detailed ATO guidance on what GST records to keep and for how long.
View on ATO websiteGST instalment method
Instead of calculating your actual GST every quarter, you can opt for the GST instalment method. This simplifies quarterly lodgement but requires an annual reconciliation.
How it works
- The ATO calculates a quarterly instalment amount based on your previous year's GST
- You pay that fixed amount each quarter (you can vary it if needed)
- At year end, you lodge an annual GST return to reconcile
- If your instalments exceeded your actual GST, you get a refund
- If they fell short, you pay the difference
Who can use it
- Businesses with GST turnover under $10 million
- Must be lodging quarterly (not monthly)
- You can opt in through the ATO portal or your tax agent
- Not suitable if your income fluctuates significantly — you may overpay or underpay
ATO Reference
GST instalment notice — how to complete your quarterly notice
ATO guidance on the GST instalment method, how the ATO calculates your instalment amount, and how to vary it.
View on ATO websiteNeed to estimate your next BAS?
Enter your quarterly sales and purchases, and our BAS estimator calculates your G1, 1A, and 1B figures — plus whether you'll owe the ATO or receive a refund.
Use the BAS Estimator →Frequently asked questions
Related guides
How to Calculate GST in Australia
Formulas, worked examples, and the divide-by-11 rule for adding and removing GST.
GST Registration Threshold
When you must register, how the $75K threshold works, and voluntary registration pros and cons.
GST-Free Items in Australia
Full list of goods and services exempt from GST — know what to exclude from your BAS calculations.
← Back to GST Calculator
Add or remove GST, generate invoices, and estimate your BAS.