BAS Calculator: Estimate Your GST, PAYG & BAS
A basic BAS estimate is GST on sales at 1A minus purchase credits at 1B, plus PAYG withholding at W2 and the income-tax instalment at 5A, less fuel tax credits at 7D. Using the worked example’s sales, purchases and withholding gives $21,636 payable. Enter figures for the same reporting period; the estimate drops cents and does not replace your accounting records.
BAS amount
$21,636.00
- 1A GST on sales
- $13,636.00
- 1B GST on purchases
- $6,000.00
- Net GST
- $7,636.00
- Direction
- payable to ATO
Show breakdown
Calculation breakdown
- G1 total sales
- $165,000.00
- G3 GST free sales
- $15,000.00
- 1A GST on sales
- $13,636.00
- 1B GST on purchases
- $6,000.00
- W2 withheld
- $9,800.00
- 5A payg instalment
- $4,200.00
- 7D fuel tax credit
- $0.00
- Net GST
- $7,636.00
- Amount
- $21,636.00
- Direction
- payable to ATO
| G1 total sales | $165,000.00 |
|---|---|
| G3 GST free sales | $15,000.00 |
| 1A GST on sales | $13,636.00 |
| 1B GST on purchases | $6,000.00 |
| W2 withheld | $9,800.00 |
| 5A payg instalment | $4,200.00 |
| 7D fuel tax credit | $0.00 |
| Net GST | $7,636.00 |
| Amount | $21,636.00 |
| Direction | payable to ATO |
This simplified BAS estimate drops cents from labels. It excludes adjustments, input-taxed sales and specialised GST treatments. Keep your records and confirm the return with your tax agent.
At a glance
- GST rate
- 10% on most goods and services sold in Australia
- Add GST
- price × 1.1; GST amount = price × 0.1
- Remove GST
- GST = inclusive price ÷ 11; exclusive price = inclusive − GST
- Rounding
- GST to the nearest cent, half a cent rounds up; BAS in whole dollars
- Note
- Register for GST at $75,000 turnover ($150,000 for non-profits); ride-share drivers from the first dollar
- Note
- Tax invoice required for sales over $82.50 including GST
- BAS
- 1A GST on sales − 1B GST on purchases, plus PAYG withholding and instalments
How it is calculated
Add GST to an exclusive amount or divide an inclusive amount by eleven to extract ten per cent GST. For a BAS estimate, drop cents from GST labels and combine credits and withholding.
GST mode: add: gst = ex × 10%; inc = ex × 1.1
remove: gst = inc ÷ 11; ex = inc − gst (round gst to cents first, then ex = inc − gst so the two add back exactly)
BAS mode (whole dollars, cents dropped, per ATO instructions):
1A = floor((G1 − G3) ÷ 11)
1B = floor((G10 + G11 − purchases_without_gst) ÷ 11)
net GST = 1A − 1B
amount = 1A − 1B + W2 + 5A − 7D; payable if ≥ 0 else refund- Rates as at 2026-09-07 from Gst
Can I lodge a BAS directly from this estimate?
Use the figures to check your understanding, then lodge from reconciled accounting records or through your BAS agent. Private use, adjustments, tax codes and accounting basis can change the amount. The estimate does not establish that every sale and purchase has been classified correctly.
Do wages go on a BAS?
Where the PAYG withholding section applies, gross payments and withholding are reported at the appropriate wages labels, including W1 and W2. Wages themselves do not include GST and are not purchase credits at 1B. Keep the reporting period consistent across the estimate.
How do you calculate GST in Australia?
GST is 10% of the price before tax, so adding it means multiplying by 1.1, and the GST amount is one tenth of the exclusive price. Working backwards from a GST-inclusive price is where people slip: the GST is one eleventh of the inclusive price, not one tenth, because the inclusive price is 110% of the base. A $1,375.00 invoice contains $125.00 of GST ($1,375 ÷ 11) and $1,250.00 before tax; taking 10% of $1,375 would give $137.50, which is wrong by $12.50. The calculator applies the right divisor in each direction and rounds to the cent the way the ATO specifies, so the exclusive price and the GST always add back to the inclusive figure exactly.
Which sales are GST-free or input taxed?
Most basic food, most health and medical services, most education courses, childcare, exports, and some other categories are GST-free: no GST is charged on the sale, but the seller can still claim credits on related purchases. Financial supplies and residential rent are input taxed: no GST on the sale and no credits on the inputs. Everything else sold by a registered business in Australia is taxable at 10%. Mixed invoices, a wholesaler selling both food and non-food lines for example, carry GST line by line, which is why the invoice generator on this site applies GST per line and why accounting systems need a tax code on every product.
How is a BAS calculated?
The business activity statement adds up the GST collected on sales (label 1A, which is total taxable sales ÷ 11), subtracts the GST paid on purchases that carry a credit (label 1B, purchases with GST ÷ 11), and adds any PAYG withholding from wages (W2), PAYG income tax instalment (5A) and other amounts, less fuel tax credits (7D). The result is payable if positive and refundable if negative. Amounts are reported in whole dollars. The estimate on this page uses those labels so it reads like the form, but it is an estimate: adjustments for private use, bad debts, the simplified GST methods for some retailers, and the choice between cash and accruals basis all change the real figures, which come from your accounting system.
When does a growing business need more than a GST calculator?
When GST is being worked out per line across hundreds of invoices, purchase orders and stock receipts a month, and the BAS is assembled from spreadsheets. Accounting software handles GST codes on transactions; the step beyond it is when inventory, purchasing and sales live in separate tools and the GST treatment of each line has to be re-keyed. An ERP carries the tax code on the product and the customer, applies it on every document, and produces the BAS labels from the ledger, which is the point at which the quarterly reconciliation stops being a project. That transition is what moving from Xero or AccountRight to an ERP looks like for most of the wholesalers we work with.
| Calculation | Input | GST | Result |
|---|---|---|---|
| Add GST | $1,250.00 ex GST | $125.00 | $1,375.00 inc GST |
| Remove GST | $1,375.00 inc GST | $125.00 | $1,250.00 ex GST |
| Remove GST, rounding | $99.99 inc GST | $9.09 | $90.90 ex GST |
| BAS estimate (quarter) | Sales $165,000 (of which $15,000 GST-free); purchases $66,000; W2 $9,800; 5A $4,200 | 1A $13,636 − 1B $6,000 | $21,636 payable |
| BAS estimate (refund) | Sales $44,000; purchases $71,500 ($2,200 without GST); capital $33,000 included | 1A $4,000 − 1B $6,300 | $2,300 refund |
Frequently asked questions
Can I lodge a BAS directly from this estimate?
Use the figures to check your understanding, then lodge from reconciled accounting records or through your BAS agent. Private use, adjustments, tax codes and accounting basis can change the amount. The estimate does not establish that every sale and purchase has been classified correctly.
Do wages go on a BAS?
Where the PAYG withholding section applies, gross payments and withholding are reported at the appropriate wages labels, including W1 and W2. Wages themselves do not include GST and are not purchase credits at 1B. Keep the reporting period consistent across the estimate.
How do I calculate GST from a GST-inclusive price?
Divide the inclusive price by 11 to get the GST, and subtract it to get the price before GST. $1,375.00 ÷ 11 = $125.00 GST, leaving $1,250.00. Do not take 10% of the inclusive price; that overstates the GST by a tenth. The calculator's "remove GST" mode does the division and the rounding.
When do I have to register for GST?
When your GST turnover reaches $75,000 a year ($150,000 for non-profit organisations), or from the start if you provide taxi or ride-sourcing services. You can register voluntarily below the threshold to claim credits on purchases. Once registered you must charge GST on taxable sales, issue tax invoices over $82.50 and lodge a BAS.
moving from Xero or AccountRight to an ERP
When GST is applied per line across thousands of documents a month and the BAS is a spreadsheet, it is time for tax codes on every product and customer. That is an ERP conversation.
Book a conversation