BAS Calculator
Calculate your Business Activity Statement amounts including GST collected, GST paid, and PAYG instalments.
Calculate your Business Activity Statement (BAS) amounts. Use the GST calculator below to work out your GST collected and GST paid for the reporting period.
- BAS is lodged quarterly (or monthly for businesses with turnover >$20M)
- Report GST collected on sales minus GST paid on purchases
- PAYG instalments may also be reported on your BAS
- Lodge online via myGov or through your tax agent
Disclaimer
This calculator provides estimates for general information purposes only. Results should not be relied upon as professional financial, tax, or legal advice. Tax rates and thresholds are based on publicly available ATO data and may change. Always consult a qualified tax agent or financial adviser for advice specific to your circumstances.
Frequently Asked Questions
How often do I need to lodge a BAS?
What happens if I lodge my BAS late?
What is BAS?
A Business Activity Statement (BAS) is a form submitted to the ATO that reports your business's GST, PAYG withholding, PAYG instalments, and other tax obligations. Most businesses lodge quarterly.
How this calculator works
Use the GST calculator to work out your BAS figures. The key BAS fields are: 1A (GST on sales — the total GST you've collected from customers), 1B (GST on purchases — the GST you've paid on business expenses), and the difference is what you owe or are owed. BAS is due quarterly: 28 October, 28 February, 28 April, and 28 July. Late lodgement attracts penalties starting at $313 per 28-day period. Small businesses with turnover under $10 million can report GST annually. Lodge online through myGov, your accounting software, or your BAS agent.
Quarterly BAS Due Dates
Q1 (Jul-Sep): due 28 October. Q2 (Oct-Dec): due 28 February. Q3 (Jan-Mar): due 28 April. Q4 (Apr-Jun): due 28 July. Via BAS agent: deferral usually granted (typically +4 weeks). Late lodgement penalty: $313 per 28-day block, max 5 blocks ($1,565). Interest on unpaid amounts: General Interest Charge (GIC) currently ~11% pa.
Key BAS Fields Explained
G1: Total sales (inclusive of GST). 1A: GST you collected on sales (G1 ÷ 11 for GST-inclusive sales). 1B: GST you paid on business purchases (input tax credits). Net GST = 1A - 1B (positive = you pay ATO, negative = ATO refunds you). W1: gross wages paid to employees. W2: PAYG withholding from wages. 5A: PAYG instalments (if you have one).
Common BAS Mistakes
(1) Claiming GST on GST-free purchases (fresh food, healthcare, education, exports). (2) Claiming GST on personal expenses. (3) Forgetting to register for GST when turnover crosses $75k (registration is retrospective, you'll owe back-GST). (4) Confusing 'cash' vs 'accruals' GST accounting methods (you choose at registration). (5) Late lodgement to avoid paying — penalty + interest costs more than the BAS itself.
Simplifying BAS Compliance
Use accounting software (Xero, MYOB, QuickBooks) — automates 95% of BAS calculation. Subscriptions $30-$90/mo are tax-deductible. Pay-as-you-go: pay BAS quarterly even if not required (smooths cashflow vs annual lodgement). Register for GST voluntarily even below $75k threshold if you have lots of GST-inclusive business inputs — claim credits back. Annual lodgement available for small turnover (<$10M) — saves time but bigger annual payment shock.
Official Sources
All calculations are performed in your browser — your data never leaves your device. Results are for general guidance only and should not be considered professional financial advice.
Built and maintained by Konstantin Iakovlev. Data sourced from the ATO and official Australian government sources.