In a Cargo Systems Messaging Service (CSMS) bulletin issued on September 23, 2026, U.S. Customs and Border Protection (CBP) published guidance on the upcoming import ban on certain polysilicon products.

The temporary final rule for the import ban is detailed in a Federal Register Notice (FRN) published by the Bureau of Industry and Security (BIS) on September 24, 2026.

Under the rule, BIS will monitor existing companies that import polysilicon or polysilicon derivatives in advance of future import adjustments on December 4, 2026. According to BIS, it will review imports for “evidence of stockpiling, limit a newly established importer’s ability to stockpile, and subject companies that are stockpiling to an import prohibition if necessary.”

Importers that become subject to a polysilicon or polysilicon derivatives import prohibition may apply for a waiver of this restriction.

The CSMS can be found here:
https://content.govdelivery.com/bulletins/gd/USDHSCBP-42c09b0?wgt_ref=USDHSCBP_WIDGET_2

The temporary final rule can be found here:
https://www.federalregister.gov/public-inspection/2026-19537/measures-to-restrict-stockpiling-of-polysilicon-and-polysilicon-derivatives-under-proclamation-11052