[tipperdog]

Banks are required to report suspicious activity to the Treasury Department. Some "suspicious activity" threshholds are known (for example, banks report cash transactions of over $20,000--edit: I'm not 100% sure the threshhold remains 20K). Some activity is secret [think: wire transfers from the mid-east], and other threshholds are discretionary [If your local bank manager thinks something weird is going on, he may contact authorities].

So, it is possible that the IRS could find out about your bank balance. However, it's highly, highly unlikely that a 200K account with normal-sized deposits coming in would raise any suspicion at all. That's (relatively) small potatoes.

OTOH, if, after returning from Party Million Cruise, you visit your local BofA branch with $400,000 cash stuffed in your duffel bag, I think you can expect a visit from some kind IRS representatives.