Builders and other tradesman
The ATO has sourced from a major industry supplier their sales information. From this they are able to match up to individual builder’s and tradies’ tax returns.
They would not only expect to see a certain level of purchases, but they would then extrapolate this out to determine an appropriate level of income that would also be expected.
This is designed to weed out the cash economy that still exists within the construction industry.
This type of benchmarking is at the forefront of ATO audit processes as they attempt to claw back GST and income tax not being paid due to cash transactions not being reported.