The ATO is very upfront when it comes to their compliance activity. Every year they publish small business benchmarks that outline what a typical business 'looks like' in different industries. If your business falls outside of those benchmarks, the ATO is likely to take a closer look at why that is.
Falling outside of the benchmarks might not indicate a tax related problem. It might mean that your business has a different business model to the norm or is performing poorly relative to others in the industry. If your business does fall outside of the benchmark however, it is important to ensure that the reasons why can be clearly articulated (preferably documented) and the reason for those differences is not tax evasion. If there is no proof as to why the business is outside of the benchmarks, the ATO is likely to simply apply the benchmark ratio and issue a revised tax assessment.
The ATO look at:
cost of sales to turnover (excluding labour)
total expenses to turnover
rent to turnover
labour to turnover
motor vehicle expenses to turnover
non-capital purchases to total sales, and
GST-free sales to total sales.
For example, for a veterinary practice with a turnover between $300,001 and $800,00, the cost of sales to turnover ratio is expected to be between 25% and 29% (averaging at 27%), and average total expenses are 78%. The cost of labour to turnover ratio is between 21% and 29% and rent is between 5% and 8%.
The benchmarks are also a useful tool for anyone wanting to understand what is typical in their industry and how they perform against the average. It might also indicate opportunities for improvement and where the business is falling behind its competitors.