The "de minimis" trade loophole that allowed cheap packages to come to the U.S. duty-free is closing. Ecommerce customers are already feeling the sting.

The fast-fashion companies didn’t specify the extent of the cost increases, but posted identical notices on their websites.

The Chinese web retailers on Friday hiked prices to offset a 120% tariff that their goods will be subject to with the May 2 end of the de minimis exemption, which has allowed retailers to import goods worth less than $800 into the US without paying tariffs.