What would you do

[percy]

I'm not sure how IRD work nowadays. Back in the day they would audit prostitutes (which back then was an illegal activity. They didn't dob in the prostitute - they just wanted teh tax

So the owner gets a tax bill for $3,000,000 for revenue not declared,with penalties,as "they just want the tax"..ie not declared revenue up to $25,000 a week over 260 weeks [5 years] is $6.6mil.
That would focus the owner's attention.What undeclared revenue.?
Perhaps with IRD proof he would ask the boss a few questions,or ask the police for their help.
The whistleblower remains an innocent bystander.