The quick answer is that it depends, but probably yes. As the name implies, a duty free shop has no ‘duty’ — or local import tax — on the goods that it sells. By buying something at Heathrow Airport in London, for instance, you don’t have to pay the import tax that the UK slaps on foreign goods (such as Russian vodka) and that a local store in London would include in its price for the same goods.

Because of this, goods at duty-free stores are generally cheaper than if you were to purchase them with the import tax inside the country. However, there are two reasons to be a little cautious: The first is that according to U.S. law, if you buy more than $800 worth of items purchased abroad (duty-free or not), then you will have to pay the import tax.  The second is that sometimes, depending on geography and exchange rates, an item may just be more expensive at duty free stores.

Basically, if you know the price of your mom’s favorite perfume at Macy’s and see it cheaper at the duty-free shop (and you dont plan on buying more than $800 of it), chances are it’s a good deal.