True story: a job I had in college was preparing taxes for people at Hewlett Jackson. At the training, they said that often had people come in to file their tax forms, and several years of back taxes, for the criminal activity they'd been arrested for.
That way, if found guilty, they wouldn't have to pay significant fines and risk more jail time for tax evasion. I was like, "that's some crazy bullshit right there. That'll never happen. What criminal would do this?"
It happened 3 times at the store I worked at from January through April.
The first two were for dealing significant amounts of weed, and the last one was for fencing stolen goods.