having been through this, I'll offer my understandings. Keeping in mind that the IRS code is so complex that even they don't understand it all.
Any transaction that involves more than $10,000 is required by law to have form 8300 filled out. This includes "cash" transactions only. "Cash" includes obviously currency but also a check is considered cash in the eyes of the irs. Credit is not considered cash.
By conventional wisdom, one would think that hey lets just deposit $9999 and avoid 8300. There's truth to that--but that's also called "Structuring"--which is a federal felony.
I've been through the structuring deal, or more specifically the place I worked for was. You DON'T want to tease a rattlesnake, you might get away with it once but they'll probably show up at some point and when they do, they'll make your live a living hell much the same as they did mine. 4 1/2 hours of being held against our will by people with automatic weapons, with the first 3 hours or so of that, the agents did not identify themselves. They don't have to. They have immunity from the law. They'll send about a dozen agents for one persons' offense. One agent per door (guarding so that nobody can leave), one agent per bathroom (so when you go take a leak or dump, they'll stand there and watch you), agents that will disable your phone lines, internet lines, remove you from your personal communications device(s), they'll disconnect the tv's, lock all the doors with you inside held at gunpoint, they'll disable your cars, guard every entrance, take your pocket knives, any protection devices (security cameras, your guns, etc)--and they KNOW where you have them, because they've been scoping your place out for months/years. You're thinking "they can't do that"...oh yes they can, and quoting an agent "we are the irs we can do whatever we want".
Link to a documentary that was done. It is not dramatized, it is exactly how it went down at the place I worked at--and there are 11 others at that workplace that can attest to it.
The IRS has too much power and they exploit it. This needs to be changed. IT is not just businesses although they tend to favor going after them, because they can (and do--again based on my experience), seize hundreds of thousands of dollars. They seized our (business's) bank accounts and the business didn't even know. They can do that. They'll also go after individuals, and they have.
It's a nightmare. My friend is for the rest of her life labeled a felon because of the IRS, and wrongly so, but they had a choice either plead guilty to the count and take a plea bargain for probation, or fight it and have a 50/50 shot at winning, but if she lost, she'd lose about $2.3M and have to spend time in federal prison. She took the probation on a plea bargain.
....And....she was SET UP FOR IT. No need to know how it happened, just know she was set up. I was watching it go down with my own eyes. Nobody knew that structuring was a thing. Now we do.
As a patriot, IF I were a veteran, and fought for the country knowing that the country would turn on the people that support it, I'd have second thoughts about living here. It is honestly a communist idea to use military tactics to go after someone in the way that they did.
So more information. There were as I remember, 16 agents at the raid. They were from all over the country. They are flown to a central location where they set up the raid(s), then they drive their cars to the raid location, armed with weapons that aren't cheap. I'm in the south central USA, one of the agents was from Oregon, one from Washingston state, California, Utah, New York, Pennsylvania, one from Vermont, one from Ohio, you get the idea. Imagine what the travel costs are. Yet you and I (the taxpayers) foot the bill for it. Rubs me wrong that our government can and does this stuff to the citizens of the usa. It should open the eyes of every American. Unfortunately, some are going to think "this guy's full of crap"--and I can't change that, all I can do is offer my experiences and hope you all understand what they can do; or is it "what they can't do" (which is not much).
Keep this in mind when you think about President Biden's proposal to make you fill out "forms" if you transact more than $600. It can't be fully policed, but I would be willing to bet that they'll darn sure try, all in the name of "more money" for the government. But hey, that's what the people voted for