There are many things you are supposed to declare upon your return to the US. These are the items you inherited, those which you bought from duty free shops and, possibly those which you brought for somebody else. This is consistent with the local regulations and you should obey such instructions. Therefore, you have to know what you must declare?
Despite the items stated above, you also have to declare the items you acquired from the US Virgin Islands, Guam, American Samoa as well as the Caribbean Basin Economic Recovery act. Particularly if you requested the merchant to send them to your place. Such items must be declared at custom offices.
You are required to make a declaration on the CBP what the actual cost of the items was, that is in the US currency. The cost must also incorporate virtually all taxes, that is the value added tax or even the custom duty tax. In case you are not sure of their real cost, give a ballpark estimate. Perhaps you did not purchase the item, may be it was a gift. You can estimate its real worth in that country of origin or you can contact the person who sent it.
What if you bought the item when on a tour? Is the product dutiable? This is a question you will more likely ask. Yes it is dutiable. You have to declare it at the cost at which you bought it or in case it was a present, at its real worth from where it originated. If you have the cash invoice, you can easily present it to the officers at the entry point. Perhaps the details will be much clear.
The hundreds of thousands of global travelers who visit the US daily are subjected to stringent inspection at entry points. They are inspected by the Customs and Boarder Protection Officials who check on compliance with customs, immigration and agriculture specifications. The job is hectic and, therefore you are recommended to learn about the whole process before you visit. If a majority are acquainted with the regulations, the process would be easier and faster.
There are agencies that have been instituted to ensure that prohibited products do not find their way in. The CBP officers are always at entry ports and assume their role to protect every citizen from unsafe products. The prohibited products are those that can injure the community health. Therefore, before you travel abroad, check with the CBP officials and talk about the products you wish to bring back. This will ensure that you do not bring back prohibited items.
You must acquire a license if you would wish to bring in some products. For instance, certain fruits and vegetables, firearms, animal supplements and selected animals. Get the license beforehand. The process of declaration and clearance would be easier.
If you live in the United States and you wish to bring back some products when you travel aboard, remember you will have to make a declaration. Get to know about the entire process. Also, obtain a license for special merchandise.
Official information at: http://www.cbp.gov/travel/international-visitors/know-before-you-go/declare