At one time,Al Capone was listed in the Guinness Book of World Records as the private citizen having the highest income for one year. The figure quoted was $105,000,000. If I remember correctly,it was in the book for many years.
Since entries must be verified,I'm guessing that they had access to Law Enforcement info,or some type documentation. Adjusting for inflation,this would have to be in the half-billion dollar range in today's money.