Simpler BAS: what goes in G1, 1A and 1B
Plain-English guide to the three GST boxes on a Simpler BAS – G1 Total sales, 1A GST on sales and 1B GST on purchases – with a worked example and ATO sources.
If your business is registered for GST and your GST turnover is under $10 million, the ATO's default way to report GST is Simpler BAS. For GST you only fill in three labels each period: G1, 1A and 1B. You don't need a GST calculation worksheet, and labels like G2, G3, G10 and G11 belong to the full reporting method, not Simpler BAS.
G1 – Total sales
G1 is all your sales for the period. That includes taxable sales (with GST), GST-free sales and input-taxed sales. You can report G1 either GST-inclusive or GST-exclusive, but you must tick which one you used.
- The ATO's guide puts sales of goods and services, sales of business assets such as vehicles and machinery, GST-free sales and input-taxed sales at G1.
1A – GST on sales
1A is the GST included in your taxable sales. If you charged 10% on top of a GST-exclusive price, it's that 10%. If you only have the GST-inclusive total, the GST is 1/11 of the total.
1B – GST on purchases
1B is the GST included in the price of things you bought for your GST-registered business. These are your GST credits. You don't report total purchases on a Simpler BAS, only the GST in them.
- You need a valid tax invoice to claim the credit on a purchase over $82.50 (GST inclusive).
- No credit if the supplier isn't registered for GST, so there's no GST in the price. The same goes for GST-free items, bank fees, stamp duty, wages and super.
- If you use something for both business and private purposes, such as a phone or a car, only claim the business share.
Worked example (made-up figures)
This quarter a sole trader invoiced $22,000 including GST, all taxable. They also bought $5,500 of materials and fuel including GST, all for the business, with tax invoices.
- G1 Total sales (GST-inclusive): $22,000
- 1A GST on sales: $22,000 ÷ 11 = $2,000
- 1B GST on purchases: $5,500 ÷ 11 = $500
- Net GST to pay: $2,000 − $500 = $1,500
Common mistakes
- Claiming GST credits on purchases from suppliers who aren't registered for GST.
- Claiming the full GST on a phone bill or car cost that is partly private.
- Leaving GST-free sales out of G1. They still go in G1, just with no GST at 1A.
- Not keeping tax invoices for purchases over $82.50.
Free tools (they run in your browser):
GST & BAS Quick Calculator – add or remove GST, estimate G1, 1A and 1B for a Simpler BAS, and check the $75,000 registration threshold
Tradie Charge-Out Rate Calculator – work out the hourly and day rate that covers your wage, super, overheads and unbillable hours, plus profit, with or without GST.
Sources
Related guides
- How to quote a job with GST (Australia)
- What a tax invoice must show (Australia)
- The car logbook 12-week rule, explained
- Do I need to register for GST? The $75,000 rule
- TPAR for tradies: paying subbies and the 28 August report
General information only, summarised from the official sources above as at the review date. It isn't legal, tax, WHS or engineering advice. Rules change and your situation may differ, so check the source or ask a professional.