Let's say I'm a freelance treasure hunter who goes around and discovers all kinds of expensive artifacts all over the world. I sell the artifacts in cash and put it into a bank. It's about 600,000 to 2 million in cash every time I do it (I know it's ridiculous, but bear with me). I pay taxes and everything. I'm not trying to hide money from the IRS. But obviously so much cash would raise questions... so would I be forced to disclose where it came from? Could I tell a bank, or the IRS, or whoever, when they ask, "It's none of your business where I got this money." Or are they allowed to investigate me and force me to disclose where I got the money without probable cause that I've done anything illegal?