In USA even if you sold cocaine...or your mom, you need to declare it on income taxes. They might not catch selling cocaine but if they catch you with undeclare

In USA even if you sold cocaine...or your mom, you need to declare it on income taxes. They might not catch selling cocaine but if they catch you with undeclared cash, they'll Al Capone you. I'm almost certain that all countries have a catch all phrase to include any gains /income.