Generally speaking, travelers get an $800 personal exemption when they travel. This only includes 1 liter of alcohol, however. You may bring home more wine or spirits than that 1 liter, but you will pay duties on that. It is important to declare all items on your customs for when you return to the United States because if Customs finds undeclared items they can seize them.
There are some exceptions. If you are traveling from the Caribbean, Andean countries, Sub-Saharan Africa, Israel, Jordan, Chile or Singapore, your items will either be duty-free or taxed at a reduced rate under the Generalized System of Preferences trade program. Similarly, if you travel to Canada or Mexico and you bring home liquor that was made in that country then it too is eligible for a reduced tax under the rules of NAFTA.
Your purchases will also be subject to state taxes. How much that tax is depends on which state you are flying into. For example, in Texas, if you are a resident you may bring home 1 quart of distilled spirits, 3 gallons of wine and 24 twelve-ounce containers of beer. If you are not a resident you are allowed to bring in 1 gallon of distilled spirits, wine or a combination of the two and 24 twelve ounce containers of beer. These allowances are subject to tax as well. Other states may have rules that are slightly different.
Often travelers confuse the purpose of the duty-free store, and mistakenly believe that items that they buy there are not subject to import duties or taxes. This is not the case. What the term duty-free means in that instance is that you are not subject to local taxes on the items. You still must declare anything you buy there on your customs form and you still must pay any applicable duties on them.
