Free BAS calculator for Australian businesses. Estimate your quarterly Business Activity Statement obligations including GST collected (1A), GST on purchases (1B), net GST payable or refundable, PAYG withholding, and PAYG instalments. Helps prepare for ATO lodgement.
Total tax withheld from employee wages
Total BAS Payable
$0.00
Payable to the ATO
Net GST
$0.00
GST payable
The Business Activity Statement is the primary way Australian businesses report their tax obligations to the ATO. For most small businesses, BAS is lodged quarterly and covers GST, PAYG withholding from employee wages, and PAYG income tax instalments.
The GST section of BAS uses a series of labels: G1 (total sales including GST), G2 (export sales), G3 (other GST-free sales), G10 (capital purchases), G11 (non-capital purchases). Labels 1A and 1B are calculated automatically: 1A is GST collected on taxable sales, 1B is GST paid on purchases.
Keep good records throughout the quarter, reconcile your bank transactions regularly, ensure all invoices include GST where applicable, and claim GST credits on all eligible business purchases. Using accounting software like OneBookPlus automates BAS calculation from your invoices and expenses.
A Business Activity Statement (BAS) is a form submitted to the ATO to report and pay several tax obligations including GST, PAYG withholding, PAYG instalments, and other taxes. Most small businesses lodge BAS quarterly.
Quarterly BAS is due 28 days after the end of each quarter: 28 October (Q1), 28 February (Q2), 28 April (Q3), and 28 July (Q4). If you lodge electronically, you may get an extra 4 weeks for some quarters.
Label 1A is the GST on sales — the total GST you've collected from customers. Label 1B is the GST on purchases — the GST you've paid on business purchases. The difference (1A minus 1B) is your net GST payable to the ATO, or refundable if 1B exceeds 1A.
PAYG instalments are pre-payments of your expected income tax. The ATO calculates an instalment amount or rate based on your most recent tax return. This is separate from PAYG withholding (tax withheld from employee wages).
Yes, if you're registered for GST, you must lodge a BAS even if you have no sales or purchases for the period. Lodge a 'nil' BAS to avoid penalties.
OneBookPlus handles invoicing, GST tracking, BAS prep, and ATO lodgement automatically.