When you fly into the US, you must fill out a customs declaration. You are required to declare money in various forms (cash, checks, etc) What they ask for and what is required by law are two different things. It's not generally illegal to allow people to volunteer information that increases the power of the state. Banks are required to declare cash deposits and international movements of funds over either $5K or $10K, I forget which. In the US, the value is $10K, but that's only for cash transactions, and it's not just banks that are required to report. "International movements of funds" are not subject to reporting requirements as such. Eric