Question: how long do you have to stay in the us for duty free?
Answer: If you're in the U.S. for less than 24 hours, none of your purchases are duty free and you'll need to pay a tax on the goods. For stays that range from more than 24 to less than 48 hours, you can bring back CA$200 worth of goods duty free. Alcohol and tobacco purchases are not included in the CA$200.