Trump revoked a tax loophole that saved companies tens of billions of dollars in fees on imports. Prices on such orders could now go up an average of 30 percent.

When President Trump pushed ahead with a 10% tariff on all Chinese merchandise, he also closed the century-old de minimis exemption, which allows packages worth under $800 to be shipped into the country duty-free.

The Chinese fast-fashion giants will get slapped with a 10% tariff — but the end of a longtime trade loophole could hit them harder.