The Office of the U.S. Trade Representative on Thursday formally opened a public comment period on the European Union's carbon border adjustment mechanism, or CBAM, asking how the levy affects American producers and exports and whether enforcement action may be appropriate to remedy any negative effects.
In the notice, the office said the comments, due Nov. 9, will help inform continued U.S. engagement with the EU on CBAM. Inside U.S. Trade, which reported the notice on Wednesday before its formal publication, said Washington regards the measure as a possible barrier to trade.
The notice's questions begin with the levy's current costs, regulatory burden and effect on market access for U.S. producers, including small and midsize ones, and extend to how the EU's pending proposals to widen it would affect them. Commenters are also asked how the rules affect American companies compared with European and other foreign competitors, and the office invites specific evidence such as affected products, trade values, lost sales and effects on jobs.
Under CBAM, EU importers of aluminum, cement, electricity, fertilizer, hydrogen, and iron and steel must declare the greenhouse gas emissions generated in making those goods and buy certificates whose price follows allowance auctions in the EU's emissions trading system. The European Commission describes the mechanism as its tool against carbon leakage, meant to make the price of imports reflect the emissions embedded in them, and says it also aims to encourage cleaner industrial production outside the bloc.
CBAM's definitive phase took effect on Jan. 1, 2026, after a transitional period that began in 2023. According to the notice, importers do not have to start paying until September 2027, but goods brought in since Jan. 1 are already accruing obligations.
When a foreign producer's own emissions data is unavailable, importers must use default values set by the EU, which the trade office says carry a punitive markup intended to push importers toward company-level figures. Company data, in turn, must be checked by a verifier accredited in the EU.
The Commission proposed in December 2025 to extend CBAM to more iron and steel products and to a new category of combined metal goods spanning more than a hundred downstream items. The Council of the EU adopted a position in June that would add more than 300 products, and the European Parliament adopted one in September that would add about 400, by the trade office's count. The three institutions must now reconcile their versions, and the first political round of those negotiations is scheduled for Oct. 20, according to a legal update from the law firm Mayer Brown. The notice says formal approval could come later this year.
In August, asked about a Financial Times op-ed by Andrew Puzder, the U.S. ambassador to the EU, Commission spokesperson Louise Bogey said the Commission did not share the characterization of the mechanism as a tariff, Bloomberg Tax reported. She called it a climate measure that is "non-discriminatory, WTO compatible, and applies equally to all third countries based on verified embedded emissions, irrespective of origin," and said that while the Commission would keep engaging on implementation, the "EU's regulatory autonomy remains non-negotiable."
The notice does not commit the administration to any particular response and names no legal authority for an enforcement step. It was signed by Amy Kreps, the acting assistant U.S. trade representative for environment and natural resources, and comments are being accepted on the government's regulations website under docket USTR-2026-0661.