If you're registered for GST, you have to lodge a Business Activity Statement (BAS). Plenty of sole traders pay someone to do it — but if your affairs are straightforward and your books are reconciled, doing it yourself is well within reach. Here's the whole process, label by label.
What a BAS is and who has to lodge one
A BAS is the form you use to report and pay GST (and sometimes PAYG instalments and other obligations) to the ATO. You must lodge a BAS if you're registered for GST — which is required once your turnover reaches $75,000 in a 12-month period. If you're under that and not registered, you generally don't lodge a BAS at all. Not sure? See GST registration for small business.
Step 1 — Reconcile your books first
A BAS is only as accurate as the books behind it. Before you start, make sure every account is reconciled for the period and every transaction is categorised. If your books are wrong, your BAS will be wrong — and an amended BAS is more work than getting it right once.
Step 2 — Work out GST on sales (label 1A)
For the quarter, total your taxable sales. The GST included in those sales is 1/11th of the GST-inclusive total. So $11,000 of taxable sales includes $1,000 of GST. That GST figure goes at label 1A (GST on sales). Remember that some sales are GST-free (most basic food, some health and education) — don't charge or report GST on those.
Step 3 — Work out GST on purchases (label 1B)
Total the GST you paid on business purchases for the quarter. You can only claim the credit where the expense is for your business and — for anything over $82.50 including GST — you hold a valid tax invoice. Exclude private-use portions and anything GST-free. That total goes at label 1B (GST on purchases).
The amount you pay (or get refunded) is simply 1A minus 1B.
Step 4 — Other labels (G1, PAYG and so on)
Most sole traders also complete G1 (total sales for the period). If you pay PAYG instalments towards your own income tax, those labels appear too, usually pre-filled by the ATO. If you have employees you'll also report PAYG withholding — but a sole trader without staff can usually ignore the payroll labels.
Step 5 — Lodge and pay
You can lodge:
- Online through ATO Online services for business, linked with your myGovID
- Through the ATO's Online services, or by the paper form if you receive one
Lodge by the due date even if you can't pay immediately — lodging on time and arranging a payment plan is far better than lodging late.
Quarterly BAS due dates (self-lodgers)
| Quarter | Period | Due date |
|---|---|---|
| Q1 | July – September | 28 October |
| Q2 | October – December | 28 February |
| Q3 | January – March | 28 April |
| Q4 | April – June | 28 July |
Due dates can be later if you lodge through a registered agent. Always confirm the current dates with the ATO.
Making it easier
ReconLink generates a BAS worksheet straight from your reconciled transactions — labels G1, 1A and 1B calculated for you, with the underlying transactions behind each number so you can check the workings. Import your statements, let the 139-vendor coding pack and AI categorise them, review, and read your BAS figures off the worksheet. The Solo plan suits one self-filing business and has a free 30-day trial; see pricing.
Frequently asked questions
Can a sole trader lodge their own BAS?
Yes. You can always prepare and lodge BAS for your own business. You only need a registered BAS or tax agent if you're paying someone else to do it for you, or your situation is complex.
What happens if I lodge my BAS late?
The ATO may apply a failure-to-lodge penalty and interest. If you're going to be late, lodge as soon as you can and contact the ATO about a payment arrangement — lodging is separate from paying.
Do I report GST on every sale?
Only on taxable sales. GST-free sales (such as most basic food and certain health and education services) are reported in your total sales but carry no GST at label 1A.
This article is general information for Australian small business owners, not tax advice. Confirm current rates, thresholds and lodgement dates with the ATO or a registered tax or BAS agent for your situation.