GST

How to Lodge BAS Online in Australia (2026 Step-by-Step Guide)

15 June 2026 · 9 min read

Quick Answer

Lodge your BAS at business.gov.au via the ATO Online Services for Business portal using your myGovID and linked ABN. Quarterly BAS is due 28 days after each quarter ends — Q4 2025–26 is due 28 July 2026. You can also lodge through registered tax or BAS agents, or compatible accounting software like Xero or SAB Account AI.

Every GST-registered business in Australia has to lodge a Business Activity Statement — a BAS. It tells the ATO how much GST you collected, how much you're claiming back, and whether you owe PAYG withholding or instalments. Get it wrong or late and you're looking at failure-to-lodge penalties starting at $313 per penalty unit (as of 2026).

The good news: lodging online is faster than posting a paper form, you get a lodgment receipt instantly, and the ATO's systems flag obvious errors before you submit. Most sole traders and small business owners can lodge a simple quarterly BAS in under 20 minutes once they've done it once.

This guide covers exactly how to do it — which portal to use, what numbers you need ready, what each label means, and what to do if you make a mistake after lodging. It also flags one critical change hitting businesses from 1 July 2026: Payday Super. If you run payroll, your cash flow planning needs to account for super being due on every payday from that date, which will affect your W1 and W2 figures on every BAS going forward.

Who Needs to Lodge a BAS?

You must lodge a BAS if your business is registered for GST. GST registration is compulsory once your annual turnover reaches $75,000 (or $150,000 for non-profit bodies). Taxi and rideshare drivers must register regardless of turnover. If you voluntarily registered for GST below those thresholds, you still have to lodge.

Your BAS may also include PAYG withholding (if you have employees or withhold tax from payments), PAYG instalments (prepaid income tax), fringe benefits tax instalments, fuel tax credits, and wine equalisation tax. For most sole traders with no employees and straightforward GST, the form is short — you're really only filling in G1, 1A, and 1B.

If you're not registered for GST, you don't lodge a BAS. You may still have an instalment activity statement (IAS) obligation for PAYG instalments, but that's a separate form and a shorter one.

Not sure if you're registered for GST? Log in to ABN Lookup (abr.business.gov.au) and search your ABN. Your GST registration status is listed publicly.

You must lodge a BAS if:

Annual GST turnover ≥ $75,000 — compulsory GST registration
Rideshare/taxi drivers — compulsory regardless of turnover
Voluntary GST registrants — must lodge even under the threshold
Businesses with employees — BAS includes PAYG withholding amounts
Not registered for GST — no BAS required (IAS may apply instead)

BAS Lodgment Periods and Due Dates in 2026

The ATO assigns you a lodgment frequency when you register for GST — monthly, quarterly, or annually. Most small businesses are quarterly. Your frequency is shown on your BAS when it's issued, and inside ATO Online Services for Business.

Quarterly due dates for the 2025–26 financial year are: Q1 (Jul–Sep 2025) was due 28 October 2025; Q2 (Oct–Dec 2025) was due 28 February 2026; Q3 (Jan–Mar 2026) was due 28 April 2026; Q4 (Apr–Jun 2026) is due 28 July 2026. If you lodge through a registered BAS agent, you may get extended due dates — typically up to 25 November for Q1 and 28 May for Q3.

Annual lodgers whose turnover is under $75,000 and who are voluntarily registered have a single lodgment due 31 October each year. Monthly lodgers (turnover above $20 million, or those who elected monthly) lodge by the 21st of the following month. Missing a due date triggers a failure-to-lodge penalty — the base unit is $313 in 2026, and penalties can stack at one unit per 28 days late, up to five units.

Q4 2025–26 BAS is due 28 July 2026 — 16 days after the new Payday Super rules start on 1 July 2026. If you have employees, your W1 (gross wages) and W2 (PAYG withheld) figures will reflect any pay runs processed under the new rules. Get your payroll records reconciled before you sit down to lodge.

Key 2026 BAS due dates:

Q4 2025–26 (Apr–Jun): due 28 July 2026
Monthly BAS: due 21st of the following month
Annual BAS: due 31 October 2026
BAS agent lodgment: extended dates apply — confirm with your agent

What You Need Before You Log In

You need three things before you can lodge online: a myGovID (the ATO's digital identity app, not to be confused with myGov), your ABN linked to that myGovID in the Relationship Authorisation Manager (RAM), and your financial records for the period reconciled and ready.

For the financial records, you need to know: total sales including GST (G1), GST-free sales if any (G3), GST collected on sales (1A), and GST credits on purchases (1B). If you have employees, you also need total gross wages paid (W1) and total PAYG tax withheld (W2). Pull these figures from your accounting software or your bank and invoice records before you open the portal — having to hunt for numbers mid-session wastes time and increases the chance of errors.

If you don't have myGovID set up yet, download the app from the App Store or Google Play and verify your identity using your Australian driver's licence or passport. The setup takes about 10 minutes. Once that's done, go to ram.business.gov.au and link your ABN to your myGovID — this is the step most people skip and then wonder why they can't access the portal.

myGovID and myGov are not the same thing. myGov is for Centrelink and Medicare. myGovID is the ATO's business identity app. You need myGovID to access ATO Online Services for Business.

Checklist — have these ready:

myGovID app installed and identity verified (Standard or Strong strength)
ABN linked to myGovID via RAM (ram.business.gov.au)
Total sales including GST (for G1)
GST collected on taxable sales (for 1A)
GST credits on business purchases (for 1B)
Gross wages paid and PAYG withheld (for W1 and W2 — if you have employees)

Step-by-Step: How to Lodge BAS Online via ATO Online Services

Go to business.gov.au and click 'Login' in the top right, then select 'ATO Online Services for Business'. Log in with your myGovID credentials. Once inside, navigate to 'Lodgments' in the left-hand menu, then select 'Activity statements'. You'll see a list of activity statements the ATO has issued — find the correct quarter and click 'Start'.

The form pre-fills some information from prior lodgments. Work through each label carefully. G1 is your total sales including GST — enter the gross figure, not the GST-exclusive amount. 1A is the GST you collected (G1 divided by 11 if all sales are taxable). 1B is the GST credits you're claiming on business purchases — again, calculated at 1/11th of the GST-inclusive purchase amount. The portal calculates your net GST automatically: if 1A exceeds 1B, you owe the ATO that difference; if 1B exceeds 1A, you get a refund.

For the PAYG withholding section, W1 is the total gross wages you paid during the quarter (before any tax was withheld), and W2 is the total PAYG tax you actually withheld from those wages. These figures must match your payroll records and your payment summaries. Once all labels are complete, review the summary page — the portal shows your net position — then click 'Submit'. You'll receive a receipt number on screen; save or screenshot it. The ATO sends a confirmation to your registered email address within one business day.

The ATO portal does not auto-save. If your session times out before you submit, you'll need to start again. Have all your numbers ready in a document before you open the portal.

Lodge in 6 steps:

1. Go to business.gov.au → ATO Online Services for Business
2. Log in with myGovID
3. Lodgments → Activity statements → select correct quarter → Start
4. Enter G1 (total sales incl. GST), 1A (GST collected), 1B (GST credits)
5. Enter W1 (gross wages) and W2 (PAYG withheld) if applicable
6. Review summary → Submit → save your receipt number

How to Lodge BAS Through Accounting Software

If you use accounting software that's ATO-approved for GST reporting — including Xero, MYOB, QuickBooks, and SAB Account AI — you can lodge your BAS directly from the software without logging into the ATO portal separately. The software connects to the ATO via SBR2 (Standard Business Reporting) and submits the BAS electronically on your behalf once you authorise it.

The advantage is accuracy: the software pulls GST figures directly from your coded transactions, so there's no manual calculation. It also keeps a lodgment history inside your account, which is useful at tax time and if the ATO ever queries a figure. The BAS is marked as lodged inside the software and you get a confirmation number — same as lodging through the portal directly.

To set this up, you need to connect your software to the ATO by entering your ABN and authorising the connection inside the software's settings. Some platforms require you to also accept the connection inside the ATO's Software ID section in Online Services for Business. Once connected, you run your BAS report for the period, review the figures, and click 'Lodge with ATO'. The process takes about five minutes once connected.

SAB Account AI calculates your GST position automatically from your invoices and expenses, and lodges directly to the ATO. No manual label entry, no switching portals.

What to Do If You Made a Mistake on a Lodged BAS

Mistakes happen. If you realise you've underreported GST — meaning you owe the ATO more than you lodged — you must correct it promptly. Small errors (under $10,000 net GST effect) can be corrected on your next BAS by including the adjustment in the relevant label. Larger errors require you to revise the original BAS directly through the portal or through your registered agent.

To revise a BAS through ATO Online Services: go to Lodgments → Activity statements → find the lodged period → select 'Revise'. Update the relevant labels and resubmit. The ATO will calculate any interest or penalty that applies. If you correct the error before the ATO finds it, penalties are generally reduced significantly — full remission is possible in some cases if you disclose voluntarily and have a good compliance history.

If you overreported — meaning you paid the ATO more than you owed — you can also revise to claim a credit. The ATO will apply the credit to your running balance or refund it, depending on whether you have other debts. If you're in doubt about whether a revision is needed, contact a registered BAS agent. The Tax Practitioners Board (TPB) maintains a register at tpb.gov.au where you can verify an agent's registration.

The ATO charges General Interest Charge (GIC) on underpaid GST from the original due date. In 2026, the GIC rate is around 11–12% per annum. Correct errors quickly — interest compounds daily.

Correction options:

Error under $10,000 net GST effect — adjust on your next BAS
Error over $10,000 — revise the original BAS via ATO Online Services
Voluntary disclosure before ATO detection — penalties usually reduced or remitted
Overpaid GST — revise to claim the credit back
Unsure — contact a registered BAS agent (check tpb.gov.au)

SAB Account AI calculates your GST, pre-fills your BAS labels, and lodges directly to the ATO — try it free and lodge your Q4 BAS before the 28 July 2026 deadline.

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Frequently asked questions

Can I lodge a BAS without an accountant?

Yes. Most sole traders and small business owners lodge their own BAS through ATO Online Services for Business using myGovID. You only need a registered BAS or tax agent if you want extended due dates or if your BAS is complex (multiple taxes, fuel tax credits, wine equalisation tax).

What happens if I lodge my BAS late?

The ATO issues a failure-to-lodge (FTL) penalty starting at one penalty unit ($313 in 2026) per 28 days overdue, up to a maximum of five units ($1,565). The ATO may remit penalties for first-time or infrequent late lodgers — call 13 28 66 and ask, but lodge first.

Do I still need to lodge a BAS if I have no income for the quarter?

Yes. If you're GST-registered, you must lodge a nil BAS — just enter zeros in the relevant labels. Failing to lodge a nil BAS still triggers a failure-to-lodge penalty.

What is the difference between a BAS and an IAS?

A BAS (Business Activity Statement) covers GST plus any other obligations like PAYG withholding and instalments. An IAS (Instalment Activity Statement) is issued to businesses that have PAYG instalment or withholding obligations but are not registered for GST. If you're registered for GST, you lodge a BAS, not an IAS.

How does Payday Super from 1 July 2026 affect my BAS?

Payday Super changes when super must be paid — from quarterly to each payday — but super payments themselves do not appear on your BAS. However, your W1 (gross wages) figure on each BAS will reflect payroll processed under the new rules, and the cash flow impact of paying super every pay cycle may affect how much working capital you have available to pay BAS liabilities on time. Reconcile your payroll records before lodging your Q4 2025–26 BAS due 28 July 2026.