If your GST turnover is under $10 million, you're on Simpler BAS and report just three GST labels:
- G1 Total sales: all your sales for the quarter, whether taxable, GST-free or input-taxed (including exports). Tick whether the figure includes GST.
- 1A GST on sales: the GST in your taxable sales (taxable amount ÷ 11).
- 1B GST on purchases: the GST credits on business purchases. You need a tax invoice for purchases over $82.50, and only the business-use share counts.
(ATO: Instructions for completing your BAS, Step 1: Sales, Step 3: Purchases.)
Worked example (Q1, July–September 2026)
| Sale | Amount | Treatment |
|---|---|---|
| Electrical repair | $1,320 | Taxable |
| Tiling | $880 | Taxable |
| Goods exported to NZ | $2,000 | GST-free export |
- G1 = $4,200 (GST-inclusive)
- 1A = $1,320 ÷ 11 + $880 ÷ 11 = $120 + $80 = $200
| Purchase | Amount | Business use |
|---|---|---|
| Materials | $440 | 100% |
| Phone | $99 | 60% |
| Laptop | $2,200 | 100% |
- 1B = $40 + $5.40 + $200 = $245.40
- Net: 1A − 1B = −$45.40, so you'd get a refund of about $45.
Report whole dollars, rounded down (G1 $4,200, 1A $200, 1B $245). No cents and no negative signs on the form.
FY2026-27 quarterly due dates (lodge and pay)
| Quarter | Due |
|---|---|
| Q1 Jul–Sep 2026 | 28 Oct 2026 |
| Q2 Oct–Dec 2026 | Tue 2 Mar 2027: 28 Feb is a Sunday and Mon 1 Mar is WA Labour Day, so the ATO moves it to the next business day (aim for 1 Mar to be safe) |
| Q3 Jan–Mar 2027 | 28 Apr 2027 |
| Q4 Apr–Jun 2027 | 28 Jul 2027 |
Lodging online may give you 2 extra weeks (not for Q2). Tax and BAS agents may have different dates. Your BAS shows your actual due date. (ATO: Due dates for lodging and paying your BAS.)
General information, not tax advice. Quillroo's GST & BAS Workbook does these calculations from your income and expense records: https://quillroo.gumroad.com/l/au-gst-bas-workbook
Published by Quillroo, a small Australian automation studio. Questions: ledgerlinetools@proton.me
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