The U.S. Department of Commerce has issued a final affirmative anti-dumping determination on imports of diphenylmethane diisocyanate (MDI) from China, assigning dumping margins of 85.11% to Wanhua Chemical and Covestro Polymers (China). Although significantly reduced from preliminary rates, combined with existing tariffs the total effective rate exceeds 120%, severely limiting Chinese MDI competitiveness in the U.S. market and reshaping global supply-chain dynamics for polyurethane buyers.
Final dumping margins
In the final determination published on April 8, 2026, the U.S. Department of Commerce set the following weighted-average dumping margins: Covestro Polymers (China) Co., Ltd. and Shandong Mingko Co., Ltd. each at 85.11%, while other Chinese entities face 159.04%. These rates apply to MDI under HTS codes 2929.10.8010 and 3909.31.0000.
Comparison with preliminary determination
The final margins are substantially lower than the preliminary determination issued on September 11, 2025. Covestro and Wanhua saw their margin drop from 376.12% to 85.11%, a reduction of 291.01 percentage points. Other Chinese companies fell from 511.75% to 159.04%, a decrease of 352.71 percentage points.
Case timeline
The investigation began on February 12, 2025, when the U.S. Special MDI Fair Trade Alliance filed a petition at the request of BASF and Dow-related parties. The USITC found reasonable evidence on March 28, 2025. The preliminary determination was issued on September 11, 2025. Due to a U.S. government shutdown, the final determination was delayed from January 23, 2026, to April 8, 2026.
Combined tariff burden
Chinese MDI exports to the U.S. already faced a base tariff of 6.5%, a Section 301 additional tariff of 25%, and a retaliatory tariff of 10% (with 24% suspended until November 10, 2026), totaling 41.5%. With the anti-dumping duty, Covestro and Wanhua now face a combined rate of 126.61%, while other Chinese companies face 200.54%.
What buyers should watch
From January to October 2025, Chinese polymeric MDI exports to the U.S. plunged 82.6% year-on-year due to the investigation. The USITC will now issue a final injury determination; if it finds material injury to the U.S. domestic industry, the anti-dumping duties will be implemented. Importers and distributors should monitor alternative sourcing options and prepare for sustained price pressure on MDI from China.
Source: Read the original report | Published: April 10, 2026