Yes, banks must report any cash deposit of $10,000 or more to federal authorities. The reporting threshold is exactly $10,000.01 or higher. The process involves the bank filing a Currency Transaction Report, which documents the identity of the person making the deposit and the source of the funds. It is important to emphasize that this reporting requirement is triggered specifically by the use of physical currency. If a customer deposits $10,000 via a wire transfer or a cashier’s check, a CTR is not triggered, because the funds in those instances are not considered "cash" under the scope of this specific federal regulation, as their origins are already fully traceable within the banking system.