See also kickbacks, slightly lower down.

Has to be mentioned explicitly despite often, but not always, being illegal.

This is probably misleading as most people present it. The IRS does require you to report illegal earnings. But the justice department can also use that against you[0].

There’s quite a bit more case law on the matter, but tl;dr is that it’s a very fluid and ill-defined area of law. Personally I expect tax returns to be used as evidence more in the future, rather than less.

0: https://scholarlycommons.law.wlu.edu/cgi/viewcontent.cgi?art...