U.S. sets minimum import prices and extra tariffs on polysilicon and solar parts

What happened

• The proclamation establishes a minimum import price (MIP) program and new tariffs for imported polysilicon and certain polysilicon derivatives to address national-security risks under section 232.

What changes (key rules)

• Effective 12:01 a.m. ET on December 4, 2026 for goods entered for consumption:
  • Importers must submit documentation at entry showing first U.S. arm’s-length resale will be at or above the MIP or under fixed pre-existing contract terms.
  • If no documentation is provided, a specific tariff equal to the applicable MIP applies.
  • If declared value is below the MIP, a specific tariff equal to the difference applies.
  • A 15% ad valorem duty applies to many polysilicon derivatives in addition to MIP-based duties (products of the UK are subject to 10% instead of 15%; for certain Trade Agreement Partners the combined duty rules are adjusted so the sum equals 15%).

By the numbers (annexed HTSUS rates)

• MIPs set in Annex I: $21.00 per kilogram for polysilicon; $100.00 per kilogram for polysilicon ingots and wafers; $0.22 per watt for solar cells; $0.38 per watt for solar modules.
• Additional ad valorem duty: generally 15% on covered downstream products (10% for the UK under this proclamation; special rules for Japan, Korea, Taiwan, Switzerland, Liechtenstein, EU regarding combined rates).

Onshoring program

• The Secretary of Commerce may solicit and approve company-specific onshoring plans that must commit to building/refurbishing U.S. facilities and start construction by January 20, 2029.
• Approved plans can receive temporary tariff offsets (e.g., import of production equipment or covered products without section 232 duties) tied to construction progress and subject to monitoring, audits, and possible rescission.

Enforcement and other details

• U.S. Customs and Border Protection (CBP) will monitor documentation; materially inaccurate documentation can lead to permanent import prohibition for the importer and affiliates and other penalties where allowed by law.
• Manufacturing drawback is available in limited cases for products of specified Trade Agreement Partners composed entirely of polysilicon from those partners.
• Annex II adds new HTSUS headings and U.S. Note 42 to implement the MIP and tariff structure.

Who this affects

• Importers, polysilicon producers, solar and semiconductor downstream manufacturers, and companies planning U.S. polysilicon, ingot, wafer, or solar cell/module production.

Where to watch next

• The Secretary of Commerce and CBP will issue rules, monitor stockpiling, and may adjust MIPs or treat imports from partners differently if partners adopt substantially equivalent measures.