I believe in the US it was already reduced to 2500$ , I think the wiki page is not yet updated.

But I believe it can also be interpreted as that if the money comes from unknown source, unjustifiable, and cash deposit. The bank can easily file a SAR report, and then the client is in big trouble.

Take the example written above, an employer pays 100$ bonus "dark money" to his employee, just off the table, where he doesn't pay taxes on that. The employee just deposits that in a bank.

So the bank sees 100$ weekly being deposited from an unknown source, so they report that to the financial crimes units.

Now the guy can't declare that income on his tax declaration since he doesn't get a receipt to justify the source. And the employer by default will not pay taxes on this on behalf of the employee.

So the employee either accepts the money or declines it. But how can the employee know if the employer pays taxes on that or not? The employer himself can do this scheme, and the employee will never know about this.

So when the cops investigate the matter, one one hand you have tax evasion, and on other hand you have money laundering and structuring.

Again I'm no lawyer, but I think this is how it's done. And I have seen many examples of this with illegal immigrants getting paid "dark money", and then being caught by the bank.

And both the workers as the employer went to jail.