Commerce Bars Polysilicon Stockpilers From Further Imports Before December Tariffs

The Bureau of Industry and Security (BIS) of the U.S. Department of Commerce issued a temporary final rule on Thursday, September 24, 2026, empowering Commerce to prohibit importers of record from making further entries of polysilicon and polysilicon derivatives if they are found to be stockpiling above historic volumes. The measure, “Measures To Restrict Stockpiling of Polysilicon and Polysilicon Derivatives Under Proclamation 11052,” is published at 15 CFR Part 705, Docket No. 260915–0004, RIN 0694–AK57, and is effective from September 22 through December 3, 2026.

The rule implements Proclamation 11052 of August 6, 2026 (91 FR 51975), “Adjusting Imports of Polysilicon and Its Derivatives Into the United States,” in which the President found that imports of polysilicon and its derivatives threatened to impair U.S. national security. On that basis he imposed minimum import prices (MIP) and tariffs under Section 232 of the Trade Expansion Act of 1962, as amended (19 U.S.C. 1862), effective December 4, 2026, and directed the Secretary of Commerce to restrict stockpiling in the interim.

Monitoring of existing importers of record

Commerce is monitoring imports to identify importers of record (IORs) stockpiling ahead of December 4, 2026. It will make a fact-specific determination based on the aggregate volume imported since Proclamation 11052 was issued, the weekly average volume imported since August 6, 2026, the weekly average between January 1 and August 6, 2026, the weekly average imported in 2025, and the use of affiliates that do not customarily import polysilicon or of new IORs.

Commerce will give U.S. Customs and Border Protection (CBP) written notice of the IORs concerned, and CBP will notify the importer and any customs brokers acting on its behalf. Those IORs will be prohibited from making further entries of polysilicon products into the United States before December 4, 2026, unless Commerce grants a waiver.

Weekly caps for newly registered importers

New IORs that registered with CBP on or after August 6, 2026 are barred, absent Commerce approval, from importing above the following weekly quantities per Harmonized Tariff Schedule of the United States (HTSUS) subheading:

• HTSUS 2804.61.00: 12 kg
• HTSUS 3818.00.0020, 3818.00.0040, 3818.00.0045, 3818.00.0050 and 3818.00.0091: 7 kg
• HTSUS 8541.42.00: 2,000 No.
• HTSUS 8541.43.00: 55 No.

Commerce says the quantities are based on historic import data and are designed to let new IORs import at or below the typical volumes brought in by existing importers, and may be adjusted if necessary to address stockpiling.

Waiver window and broker obligations

BIS opened a submissions window for import prohibition waivers between September 22 and December 3, 2026. Applications must be filed in PDF, limited to 30 pages including attachments, to Polysilicon232@bis.doc.gov, and must cover organization and beneficial ownership, projected volumes and use of imports, legitimate business purpose, and a certification signed by a senior official under penalty of perjury. Commerce intends to respond within 14 days of receipt and may grant a 48-hour window to correct an incomplete filing.

Customs brokers entering polysilicon products between September 22 and December 4, 2026 are reminded of their duty not to file or assist in filing false claims, documents or affidavits. Evasion may trigger CBP enforcement, including proceedings to revoke or suspend a broker’s license under 19 CFR 111.53 or penalties under 19 U.S.C. 1641.

National security rationale

Commerce states that polysilicon is the base material for semiconductors, which underpin digital products and services and the defense industrial base, including radar, communications, electronic warfare, cybersecurity and missile and drone guidance systems, and is also essential for solar products used in U.S. defense programs. It adds that trade data from the week after Proclamation 11052 was published showed dramatic increases in polysilicon imports from some IORs compared with their historic weekly averages, suggesting stockpiling was already under way.

The rule also removes the aluminum and steel inclusions process, following Proclamation 11021 of April 2, 2026 (91 FR 18201), which terminated the derivatives inclusions process established in Proclamations 10895 and 10896 of February 10, 2025 and Proclamation 10962 of July 30, 2025. BIS invoked good cause under 5 U.S.C. 553(b)(B) and 553(d)(3) to waive prior notice, public comment and the delayed effective date, and obtained a new information collection under OMB control number 0694–0149. The contact is Stephen Astle, Director, Defense Industrial Base Division, Office of Strategic Industries and Economic Security.

The rule gives Washington a three-month enforcement lever over the solar-grade silicon and semiconductor supply chain before the minimum import prices and tariffs take effect, and puts importers, their affiliates and their customs brokers on notice that stockpiling in the interim can cost them access to the U.S. market.

Source: Federal Register, Vol. 91, No. 184, September 24, 2026, Rules and Regulations, p. 60505 (official reference: 2026-19537).