How the U.S. Customs Service Works

It's very important to know what you must declare or reveal on an official CBP declaration form (informally called the "customs form") before re-entering the country by plane or ship. You may bring foreign currency back into the United States, but you must declare all monetary instruments including traveler's checks, money orders, gold coins, cash, checks, promissory notes, securities or stocks. There is no limit to the amount of money that can be brought across the U.S. border, but if you have more than $10,000 you must report it to the CBP on your declaration form [source: U.S. Customs and Border Protection].

Otherwise, anything that you did not have when you left the country must be declared, including:

• Anything you bought (including from duty-free shops or on a ship or airplane)
• Anything you inherited or received as a gift (you'll have to estimate the fair market price of the gift)
• Anything you brought home for a friend
• Anything you plan to use or sell in your business
• Alterations or repairs to anything you took abroad and brought back (for example, tailoring of a suit in Hong Kong)
• Anything you bought (or received as a gift) in an insular possession country (America Samoa, Guam, the U.S. Virgin Islands) or any Caribbean Basin Initiative country (see the sidebar) and that is being shipped directly to your home (this is different from the usual procedure for mailed items)

All this means that you should save your sales receipts (no matter what language or currency) in case you're asked to produce them and that you should pack the items you're declaring separately (perhaps in a carry-on bag) in case officials want to see them.

You declare these items by filling out the U.S. customs form you will receive on the airplane or in the airport before you arrive at the customs area. The form, which also asks for basic information related to your trip, requires that you list each item in the above list and how much it cost. If you're traveling with your immediate family, personal exemptions may be combined on one form [source: U.S. Customs and Border Protection].

If you are returning from any one of the following Caribbean Basin countries, your duty-free exemption is $800: Antigua and Barbuda, Aruba, The Bahamas, Barbados, Belize, British Virgin Islands, Dominica, Grenada, Guyana, Haiti, Jamaica, Montserrat, St. Kitts and Nevis, St. Lucia, St. Vincent and the Grenadines, and Trinidad and Tobago [source: U.S. Customs and Border Protection].