Ever since a foiled terrorist plot in 2006 in which liquid explosives were to be used to blow up planes traveling between the United States and United Kingdom, flying with any sort of liquid has become more complicated for travelers. While you could once bring a bag of wine on your flight as a carry-on, customs and airlines now typically require you to pack alcohol – often to exacting specifications – in your checked bags.

Carry-on Restrictions

You can bring alcohol on your flight with you if you keep portions of 3.4 ounces or less in your quart-sized plastic bag with your toiletries. Most miniature nip bottles are 1.7 ounces, so you can bring alcohol in this form on your flight. In international airports, alcohol purchased at the duty free store can be carried on your flight if it is given to you in a tamper-proof bag with a receipt or sent to the duty free desk at your departure gate. But this alcohol can often only be carried on from the airport it was purchased in. Many international airports, particularly within Europe or in Canada on the way to the United States, require passengers to go through a security check when changing planes. If you change planes upon landing in the United States, the alcohol needs to be transferred to your checked bag after you clear U.S. Customs.

Checked Luggage Restrictions

Each airline has specific restrictions for checking alcohol in your hold luggage, but the general rule is that it must be packaged to completely prevent breakage, which could damage other customers luggage and property. Certain carriers srequire foam padded packs. Some airlines, such as Southwest Airlines, allow customers to purchase appropriate packaging at the ticket counter, but you usually have to pack your alcohol before getting to the airport.

How to Pack Alcohol Safely

Typical cardboard alcohol transport boxes are not adequate for commercial air travel due to a lack of padding. If you are transporting an entire case or half case of alcohol, find a foam container specifically designed for the shape of wine or spirits bottles your are transporting. Shipping stores and large wine emporiums typically stock these. If you are transporting a small number of bottles and want to pack them in your luggage, seal them in a leak-proof bag and then pack them with cushioning, such as bubble wrap or clothing.

Bringing Alcohol Through Customs

Buying something in a duty-free store when traveling outside the country does not automatically mean you can bring it back into the United States. Beverages that are more than 70 percent alcohol by volume can not be packed in your luggage. U.S. Customs and Boarder Patrol allows a maximum on 5 liters of alcohol between 24 and 70 percent alcohol by volume. Lower alcohol content items are not limited, as long as they are intended for personal consumption, not resale. Declare the alcohol you are transporting on your customs form and pay the appropriate duty to the customs officer, typically around $1 to $2 for wine and beer, while the amount for spirits varies by type, as of publication.