BAS Calculator Australia
Your quarterly GST position in seconds — Fin works out 1A, 1B and the net amount payable (or refundable), with the method shown.
Estimated amount payable this BAS
$500.00
- 1A — GST on sales (taxable sales ÷ 11)
- $1,000.00
- 1B — GST credits (purchases ÷ 11)
- −$500.00
- Net GST for the quarter
- $500.00
Figures above keep the cents; the ATO form uses whole dollars, so drop the cents when you lodge. Assumes all purchases entered are creditable and you account on a cash basis. Indicative only — general information, not tax advice.
Free to start. Connect a bank or drop in a statement.
How the BAS GST section works
The GST part of a quarterly BAS comes down to two numbers. 1A is the GST you collected: your GST-inclusive taxable sales divided by 11. 1B is the GST you can claim back: your GST-inclusive creditable business purchases divided by 11. The net GST is 1A minus 1B — positive is payable to the ATO, negative is a refund. If you pay PAYG instalments, that amount is added to the same statement.
| You want | Do this | Example |
|---|---|---|
| GST on sales (1A) | taxable sales ÷ 11 | $11,000 → $1,000 |
| GST credits (1B) | purchases ÷ 11 | $5,500 → $500 |
| Net GST | 1A − 1B | $1,000 − $500 = $500 |
General information, not tax advice. Fuel tax credits, wine equalisation, luxury car tax and GST-instalment methods aren’t modelled — confirm your BAS with the ATO or your accountant.
BAS — common questions
How do I calculate my BAS?
Take your GST-inclusive taxable sales for the quarter and divide by 11 — that is your 1A (GST on sales). Divide your GST-inclusive creditable business purchases by 11 — that is your 1B (GST credits). Your net GST is 1A minus 1B: positive means you pay the ATO, negative means a refund. Add any PAYG instalment to get the total BAS position.
What are 1A and 1B on the BAS?
1A is the GST you collected on sales; 1B is the GST credits you can claim back on business purchases. Both are one-eleventh of the GST-inclusive amounts, because GST is 10% of the pre-GST price.
When is the BAS due each quarter?
Standard quarterly due dates are 28 October (Jul–Sep quarter), 28 February (Oct–Dec), 28 April (Jan–Mar) and 28 July (Apr–Jun). Lodging online or through a registered agent can extend some of these — check your ATO account for your exact dates.
Do I need to lodge a BAS if I had no activity?
Yes — if you are registered for GST you lodge every period, even a nil BAS. Lodging nil on time keeps your account clean and avoids follow-up.
Cash or accruals — which figures go in?
On a cash basis you report GST in the quarter you were actually paid (most small businesses); on accruals you report when you invoice. This calculator assumes cash-basis figures — use whichever basis your GST registration uses.
Did you know?
In 1951 Australia's top marginal income tax rate was 75%, charged on incomes above £10,000; from 1955 until the mid-1980s it sat at 67%.
Wikipedia's rate history: 'the top marginal tax rate for incomes above £10,000 (equivalent to $425,000 today) was 75 per cent' in 1951, and 'From 1955 until the mid-1980s the top marginal tax rate was 67 per cent'. The year-by-year tables then show 60% in 1983–86, 49% in 1987–88 and 47% from 1990–91.
Source: Wikipedia — Income tax in Australia ↗The Medicare levy began at 1% of taxable income when Medicare launched in February 1984; it has since doubled to 2%, the last step taken on 1 July 2014.
Wikipedia: 'When Medicare was introduced by the Hawke Labor government in February 1984, it was accompanied by a Medicare levy to help fund it', set 'at 1% of personal taxable income', and 'From 1 July 2014 the Medicare levy rose from 1.5% to 2.0%'.
Source: Wikipedia — Income tax in Australia ↗Walk into BAS time already done
Connect your bank and Fin tracks the GST on every transaction through the quarter — so 1A and 1B are ready before you are. Free to start, no card needed.
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Terms used on this page
Full glossary →- BAS (Business Activity Statement)The form GST-registered businesses use to report GST and PAYG.
- Tax treatment (GST treatment)The code that decides which activity-statement label a transaction feeds.
- Input taxedSales with no GST that also deny credits on related purchases.
- BAS Excluded (out of scope)Money that is not a supply and does not appear on the activity statement.
- Capital purchase (GST on Capital)An asset you buy to use over years — G10 on the BAS, then depreciated.
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