Your sales, purchases and payroll for the quarter
All amounts in $ for one quarter. Change any figure and the page recalculates. Yellow boxes are waiting for an entry.
How the BAS amount builds up
GST on your sales, less GST on your purchases, plus the tax you withheld from wages, plus your income tax instalment, less any variation credit.
From the labels to the amount owing ($)
Checks on your figures
What goes on each BAS label
BAS labels are reported in whole dollars, with cents left off. Labels marked "for information" are reported but do not change the amount you pay.
Quarterly BAS due dates for 2026-27
When a due date falls on a weekend, you can lodge and pay on the next business day. A registered tax or BAS agent can often lodge later than the standard date.
About this calculator
Purpose. To estimate the amount payable or refundable on one quarterly Business Activity Statement for an Australian business, from figures you have already sorted into taxable, GST-free and input taxed, and to show the labels and the due date.
Assumptions and why we chose them. You can change every assumption above. Rates are as at , for the 2026-27 financial year.
- GST at 10%. GST in an amount that includes GST is one eleventh of it. Labels are rounded down to whole dollars, as the ATO allows.
- Sales you enter, less the sales with no GST, are standard taxable sales at 10%.
- Purchases you enter, less the ones with no GST, carry GST and you hold a tax invoice for each. The business use percentage, 100% by default, reduces the GST you claim back for private use.
- The example (50,000 of sales, 11,000 of capital and 22,000 of other purchases, 5,000 withheld from 20,000 of wages, a 700 instalment) is a typical quarter for a small employer.
- The 12 month turnover defaults to an illustrative 180,000. GST turnover is your sales without GST, other than input taxed sales.
- Due dates are the standard ATO dates. Agent dates shown are the usual tax agent lodgment program dates for electronic lodgment and depend on your agent's lodgment record.
Limitations and their effect.
- It does not decide whether a sale or purchase is taxable, GST-free or input taxed. A wrong classification changes 1A or 1B.
- It does not cover GST groups, the margin scheme, sale of a going concern, imports and deferred GST, financial supply apportionment, adjustments, fuel tax credits, wine equalisation tax, luxury car tax or the FBT instalment. Any of these can add to or reduce the amount.
- Cash or accrual reporting changes which invoices fall in the quarter, not how GST is worked out. Use one basis for the whole BAS.
- It does not check your PAYG withholding against the tax tables or your instalment against your ATO notice.
- Weekend dates move to the next business day here; public holidays are not taken into account.
- A refund can be used by the ATO to pay other debts on your account first.