10. How much cash may I bring with me for my trip?
There is no limit on the total amount of money or monetary instruments that may be brought into or taken out of the United States. However, if you transport or cause to be transported, more than $10,000 in monetary instruments on any occasion into or out of the United States, or if you receive more than that amount, in behalf of someone else and then transport it, you must file a Customs Form 4790 with U.S. Customs. Failure to comply can result in civil and criminal penalties, including seizure of the currency or monetary instruments. Monetary instruments include U.S. or foreign coins, currency, traveler's checks, money orders, and negotiable instruments or investment securities in bearer form are all considered when determining the total $10,000 reporting requirement.
You must do paperwork in advance, if not you get fined, not taxed my bad.
You also have to submit proof its your income, ie bank statements.