Being a tattle-tale pays if we're talking about turning in tax cheaters to the IRS. It's no secret that the US tax system is complicated and messed up in more ways than one. The large amount of rules, regulations, exemptions and loopholes makes it easy for people to cheat by paying less than what they owe.
That's why, since 2006, the IRS instituted a new whistle-blower program to strengthen then one that has existed for years. If you are an informant in a tax cheating case, they will give you a minimum of 15%, and a maximum of 30% of the amount they collect!
There are some stipulations: The total amount disputed has to be at least $2 million, and if it's an individual, their income must exceed $200,000. Either way, it's a great incentive to keep people honest.