ACC has spent more than $80,000 investigating 108 Western Bay of Plenty clients since 2012. This did not include investigation by ACC employees.
The number of investigations in each year has decreased. There were 44 investigations in 2012 at a cost of $11,192 and 14 investigations last year costing $18,903.
In the year to June, there had been 12 investigations.
ACC senior media adviser Stephanie Melville said ACC could not provide information about the measures used to investigate clients.
"It would be inappropriate to do so as it would prejudice the maintenance of the law, including the prevention, investigation and detection of offences, and the right to a fair trial."