For many Australian small business owners, “turnover” is more than just a metric—it’s a critical threshold for GST registration, eligibility for government grants, and business valuation. While most people are familiar with “Annual Turnover” (the total for a set financial year), a Rolling 12-Month Turnover provides a much more accurate, real-time snapshot of your business’s health.

Here is how to calculate it, why it matters, and how it differs from standard annual reporting.

What Is Rolling 12-Month Turnover?

Unlike a fixed financial year (July 1 to June 30), a rolling 12-month turnover is a continuous calculation. Each month, you add the most recent month’s sales to your total and drop off the sales from the month that occurred 13 months ago.

This “rolling” nature ensures your data is always up-to-date, making it the preferred method for monitoring seasonal businesses or evaluating growth trends without waiting for the end of the financial year.

Step-by-Step: Calculating Your Rolling Total

You don’t need complex software to track this. You can easily manage it in a spreadsheet.

1. Gather Your Sales Data: Collect your gross income from sales for each of the last 12 months. Remember, the Australian Taxation Office (ATO) defines “GST Turnover” as your gross income from sales connected with Australia, excluding GST and sales of capital assets.
2. Sum the Total: Add up the gross sales figures for the previous 12 months.
3. The “Roll” Process:
   • Next month, add your new monthly sales figure to your total.
   • Subtract the sales figure from the month that is now 13 months old.
   • The resulting number is your new “Rolling 12-Month Turnover.”

Example: To calculate your rolling turnover for June 2026, you would sum your gross sales from July 2025 to June 2026. When July 2026 sales figures are finalized, you add July 2026 to the total and remove July 2025.

Why the Rolling 12-Month View Is Critical

• GST Registration Thresholds: The ATO requires you to register for GST if your current GST turnover is $75,000 or more. Critically, the ATO looks at your current month plus the previous 11 months. If your rolling 12-month turnover hits this $75,000 threshold at any point, you must register for GST.
• Smoothing Out Seasonality: If your business has a busy December but a quiet January, a fixed financial year view can hide your true average performance. A rolling view shows you how your business is trending regardless of the calendar.
• Proactive Decision Making: Waiting for June 30 to assess your business performance is risky. A rolling calculation alerts you to downward trends early, giving you time to pivot your marketing or cost-management strategies.

Tips for Maintaining Accurate Data

• Use Gross Figures: Always use the gross income from sales before any expenses, taxes, or costs are deducted.
• Exclude Exclusions: Per ATO guidelines, ensure you exclude sales of capital assets (like selling a company vehicle) and any input-taxed supplies when calculating your GST turnover.
• Consistency is Key: Whether you use an Excel spreadsheet or cloud accounting software (like Xero or MYOB), keep the calculation method consistent so your month-to-month comparisons are valid.
• Automate It: If you use cloud accounting, most platforms have a “Profit & Loss” or “Sales” report that allows you to set a custom date range. Simply set it to the last 12 months and refresh it every time you close your books for the month.

Disclaimer: This guide is for educational purposes and does not constitute financial or tax advice. Because GST thresholds and definitions can change, always check the ATO website or consult with your registered tax accountant to ensure your specific business calculations comply with current legislation.