BAS Worksheet Generator

Understanding BAS Lodgement and Why Preparation Matters

A Business Activity Statement (BAS) is a tax reporting form lodged with the Australian Taxation Office to report and pay GST, PAYG withholding, PAYG income tax instalments, and other obligations. Most businesses registered for GST must lodge a BAS either quarterly (for turnover under $20 million) or monthly (for larger businesses or those that elect to lodge monthly). The due date is generally the 28th day of the month following the end of each quarter, though registered tax agents receive an extended deadline. Missing a lodgement or paying the wrong amount can attract ATO penalties and general interest charges, which is why preparing a worksheet before submitting through the ATO Business Portal or accounting software is strongly recommended.

Using a preparation worksheet - like the one above - lets you work through every label methodically before you commit to a lodgement. You can reconcile your accounting software reports (GST Summary, Profit & Loss, Payroll Summary) to each BAS field, check that your 1A and 1B figures align with your GST reports, and spot any uncoded transactions or timing differences before they become ATO queries. The worksheet also serves as a record of how you arrived at each figure, which is invaluable if the ATO ever reviews your account. Always lodge your official BAS through the ATO Online Services for Business, through your accounting software's BAS lodgement feature, or via your registered BAS or tax agent - this worksheet is a preparation aid only.

Key BAS Labels Explained

G1 (Total Sales): All sales including GST-free and input-taxed sales. 1A (GST on Sales): GST collected, typically G1 minus GST-free amounts divided by 11. 1B (GST Credits): GST paid on business purchases, your input tax credits. T1/T2/T9: PAYG income tax instalments for businesses that pay tax by instalment rather than in a lump sum. W1–W4: Total wages paid and the PAYG tax withheld from employees and contractors during the period.

How to use this BAS worksheet generator

1. Run your accounting software's GST Summary, Profit & Loss, and Payroll Summary reports filtered to the BAS period (quarterly or monthly) and have them open alongside this tool.
2. Enter each BAS label from your reports — start with G1 (total sales), then 1A (GST on sales) and 1B (GST credits), followed by any PAYG instalment amounts (T9) and payroll figures (W1 and W4).
3. Check that your 1A figure equals your GST Collected account balance and that 1B equals your GST Paid account balance — use our GST Reconciliation Generator if there is a discrepancy before proceeding.
4. Download the completed worksheet as a PDF to keep as a record of your BAS workpapers, then lodge the official BAS through ATO Online Services for Business, your accounting software, or your registered BAS agent.

What is the difference between quarterly and monthly BAS lodgement?

Most businesses with annual GST turnover under AU$20 million lodge quarterly BAS, due on the 28th day following each quarter end (28 October, 28 February, 28 April, and 28 July). Businesses with turnover of AU$20 million or more must lodge monthly. Businesses can voluntarily elect to lodge monthly if they prefer more frequent reporting — this can be useful for those that regularly receive GST refunds (such as exporters). If you use a registered tax agent or BAS agent, you typically receive an extended lodgement deadline of around four to six weeks beyond the standard date.

Do I need to include PAYG withholding on the BAS every quarter?

It depends on your withholder category. Small withholders (those who withheld AU$25,000 or less in the previous year) report and pay PAYG withholding quarterly at label W4 on the BAS. Medium withholders (AU$25,001–AU$1 million) pay monthly — but they still report on the quarterly BAS. Large withholders (over AU$1 million) pay more frequently. If you are a small withholder, both the W1 (total wages) and W4 (tax withheld) amounts must reconcile to your STP data and payroll records for the quarter.

What happens if I lodge the BAS late or pay late?

Late lodgement attracts a Failure to Lodge (FTL) penalty — currently AU$313 per 28-day period (or part thereof) for small businesses, capped at a maximum based on the lodgement type. Late payment of any amount owed on the BAS accrues the General Interest Charge (GIC), which compounds daily at the ATO's published rate (approximately 11% per annum as of FY2025-26). If you know you cannot pay the full amount, it is still important to lodge on time to avoid the FTL penalty — you can then contact the ATO to arrange a payment plan for the outstanding amount.