Over the years I've had clients who were investigated by the Inland Revenue Department following anonymous tip-offs.
Some of them were false alerts, and some cases could be chalked up to disgruntled ex-employees seeking revenge on their former employer.
An investigation can start in a number of other ways. Industries that deal heavily in cash, such as taxis or bars, will be on the IRD's radar.
Property sellers have been susceptible to rumours about selling houses tax free because of no capital gains tax - not only are there those who have missed the point of "intention to sell" , which is proven by notes on the bank's files, but some have tried to sell properties through family members and other entities to avoid paying tax.
The IRD has dedicated $6.65 million a year to enforce property tax compliance, to return $45 million in tax.