How much do I owe on my BAS?
Type your sales and purchases for the period, including GST, and any PAYG amounts. The page works out the BAS labels 1A, 1B and T11 and the net amount you pay the ATO or get back.
- Net amount
- $3,000.00
Net amount for this BAS: $3,000.00. You pay the ATO.
- Pay or refund
- You pay the ATO
- GST on sales (1A)
- $5,000.00
- GST credits (1B)
- $2,000.00
- Net GST
- $3,000.00
- PAYG instalment (T11)
- $0.00
- PAYG withheld (W2)
- $0.00
Net amount: $3,000.00. Net amount for this BAS: $3,000.00. You pay the ATO.
The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use
How to calculate
Works out the GST on sales (1A), GST credits on purchases (1B), PAYG withholding and PAYG instalment for an Australian business activity statement, and the net amount to pay or get back.
Example with the default inputs (Total sales (G1) $55,000.00, GST-free sales and exports (G2 + G3) $0.00, Purchases (G10 + G11) $22,000.00, Purchases with no GST in them $0.00, PAYG tax withheld (W2) $0.00, PAYG instalment income (T1) $0.00, PAYG instalment rate (T2) 0%): Net amount for this BAS: $3,000.00. You pay the ATO.
Method: 1A = (G1 − GST-free sales) ÷ 11; 1B = (purchases − purchases with no GST) ÷ 11; T11 = T1 × T2 ÷ 100; net = 1A − 1B + W2 + T11. A negative net is a refund.
- GST is 10%, so the GST in a GST-inclusive amount is one eleventh of it (ATO).
- Sales and purchases are typed including GST, as on the BAS labels G1, G10 and G11.
- The page does not apply adjustments (1G, 7), fuel tax credits, wine equalisation tax, luxury car tax, or a PAYG instalment varied from the ATO amount. It is an estimate, not tax advice.
Worked examples
Each example is checked against the calculator on every build.
- Total sales (G1) $55,000.00, Purchases (G10 + G11) $22,000.00 gives GST on sales (1A) $5,000.00, GST credits (1B) $2,000.00, Net GST $3,000.00, Net amount $3,000.00, Pay or refund You pay the ATO.Source: ATO, Quarterly GST reporting, https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/when-and-how-to-report-and-pay-gst/quarterly-gst-reporting
- Total sales (G1) $33,000.00, GST-free sales and exports (G2 + G3) $5,500.00, Purchases (G10 + G11) $13,200.00, Purchases with no GST in them $2,200.00, PAYG tax withheld (W2) $4,100.00, PAYG instalment income (T1) $30,000.00, PAYG instalment rate (T2) 4.5% gives GST on sales (1A) $2,500.00, GST credits (1B) $1,000.00, Net GST $1,500.00, PAYG instalment (T11) $1,350.00, Net amount $6,950.00.Source: ATO, Quarterly GST reporting, https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/when-and-how-to-report-and-pay-gst/quarterly-gst-reporting
- Total sales (G1) $11,000.00, Purchases (G10 + G11) $66,000.00 gives Net GST -$5,000.00, Net amount -$5,000.00, Pay or refund The ATO refunds you.Source: ATO, Quarterly GST reporting, https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/when-and-how-to-report-and-pay-gst/quarterly-gst-reporting
- Total sales (G1) $100.00 gives GST on sales (1A) $9.09, Net amount $9.09.Source: ATO, Quarterly GST reporting, https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/when-and-how-to-report-and-pay-gst/quarterly-gst-reporting
How it works
All amounts are in Australian dollars and include GST where the label does. The GST rate is 10%, so the GST in a GST-inclusive amount is that amount ÷ 11.
- GST on sales (1A) = (total sales G1 − GST-free sales and exports) ÷ 11.
- GST credits (1B) = (purchases G10 + G11 − purchases with no GST in them) ÷ 11.
- Net GST = 1A − 1B.
- PAYG instalment (T11) = instalment income (T1) × instalment rate (T2) ÷ 100. Leave both at 0 if you do not pay instalments, or if you pay the ATO's set amount (then add it to W2 yourself).
- Net amount = 1A − 1B + PAYG withheld (W2) + T11. A positive amount is paid to the ATO; a negative amount is refunded.
Rules: GST-free sales cannot be more than G1, and purchases with no GST cannot be more than total purchases; the page gives no answer and says why. The arithmetic is exact on the typed amounts and nothing is rounded until it is shown, to the cent, halves up. The ATO lets you round GST on the BAS to whole dollars; this page shows cents.
Not modelled: GST adjustments, fuel tax credits, wine equalisation tax, luxury car tax, fringe benefits tax instalments, and varied PAYG instalments. It is an estimate, not tax advice.
When the data is out of date
The 10% rate is checked for the 2025-26 and 2026-27 financial years. After June 30, 2027 the page keeps using it and says so above the result.
Worked examples by hand
$55,000 of sales and $22,000 of purchases. 1A = 55,000 ÷ 11 = $5,000; 1B = 22,000 ÷ 11 = $2,000; net GST and net amount $3,000 to pay.
A quarter with GST-free sales, wages and an instalment. G1 $33,000 with $5,500 GST-free: 1A = 27,500 ÷ 11 = $2,500. Purchases $13,200 with $2,200 that had no GST: 1B = 11,000 ÷ 11 = $1,000. Net GST $1,500. W2 $4,100. T11 = 30,000 × 4.5% = $1,350. Net amount = 1,500 + 4,100 + 1,350 = $6,950.
A refund. Sales $11,000 and purchases $66,000: 1A $1,000, 1B $6,000, net −$5,000, a refund.
$100 of sales. 1A = 100 ÷ 11 = $9.0909…, shown $9.09.
Other questions people ask
How do I calculate GST for my BAS?
GST is 10%, so the GST inside a GST-inclusive price is one eleventh of it. GST on sales (1A) is your taxable sales divided by 11; GST credits (1B) are your purchases that included GST divided by 11. Net GST is 1A minus 1B.
What goes in G1, G2 and G3?
G1 is all your sales in the period, including GST. G2 is export sales and G3 is other GST-free sales; both are part of G1 but carry no GST, so they are taken out before dividing by 11.
What are G10 and G11?
G10 is capital purchases (equipment, vehicles) and G11 is all other purchases, both including GST. Only purchases that had GST in them give a GST credit; leave out wages, bank fees, and GST-free items.
What are W1 and W2?
W1 is the total of wages and other payments you made, and W2 is the tax you withheld from them. W2 is added to the amount you owe on the BAS.
How is the PAYG instalment worked out?
If you pay by rate, the instalment is your instalment income (T1) times the rate the ATO gave you (T2). For example, $30,000 at 4.5% is $1,350.
What if the net amount is negative?
A negative amount means your GST credits are larger than the GST and PAYG you owe, so the ATO refunds the difference. This is common in a quarter with a big purchase.
Do I need to report every label?
Businesses with GST turnover under $10 million use Simpler BAS and report only G1, 1A and 1B for GST. Larger businesses use full reporting. The arithmetic for 1A and 1B is the same.