It's not only about them being unable to assess if you reported all your lawful income. It may be more about whether they can assess whether you have no lawful

It's not only about them being unable to assess if you reported all your lawful income. It may be more about whether they can assess whether you have no lawful income yet seem to be filthy rich. Remember Al Capone. He would have never got caught if it was not for being caught for tax-evasion.