Once you have exceeded your duty free exemption amount, you will be required to pay a flat rate of duty on the next $1000 worth of merchandise. Any amount greater than this will be dutiable at whatever rates apply for the country from which you are returning. We surveyed the US Customs site and found that flat duty rates range from 2 – 4% and individual duty rates (on merchandise exceeding your exemptions and initial $1000 worth of merchandise) range from $300 - $1100.
If you do owe duty, you will be required to pay it upon re-entering the United States. The U.S. Customs site lists the following as acceptable forms of payment:
U.S. currency (foreign currency is not acceptable).
Personal check in the exact amount, drawn on a U.S. bank, made payable to the U.S. Customs Service. You must present identification, such as a passport or driver's license. (The Customs Service does not accept checks bearing second-party endorsements.)
Government check, money order, or traveler's check if it does not exceed the duty owed by more than $50.
In some locations, you may pay duty with credit cards, either MasterCard or VISA.