The United States has officially scrapped a long-standing tariff exemption for Chinese goods under $800, imposing steep duties on low-cost imports that threaten the business models of major e-commerce platforms such as Shein and Temu.

Starting Friday, goods shipped commercially from China will face tariffs of up to 145%, while items entering through the US Postal Service will incur duties of 120% or $100, rising to $200 next month. The decision, first announced in April, is part of a broader White House strategy to combat the illicit import of synthetic opioids.

“This is a critical step in countering the ongoing health emergency,” the White House stated, linking the move to national security concerns over fentanyl trafficking from China.

The removal of the “de minimis” exemption means even low-value shipments are now subject to steep levies. “It will squeeze already-thin margins and drive up end prices,” noted EY chief economist Gregory Daco.

The new tariffs are the latest in a growing trade conflict between the US and China. Washington has also imposed 25% duties on Chinese autos, steel, and aluminum, while Beijing has responded with 125% tariffs on US goods.

Despite the escalation, Chinese e-commerce stocks like PDD (Temu’s parent) and Alibaba posted gains on Friday, buoyed by hopes of easing trade tensions and market anticipation of the policy shift.

Reports suggest Shein is postponing its UK IPO due to the new tariff regime, underlining its potential impact on the global e-commerce landscape.