The EU's Carbon Border Adjustment Mechanism: What It Is and Why It Matters

The Problem CBAM Was Designed to Solve

The core concern motivating CBAM is carbon leakage — the risk that stricter EU climate policy will simply push carbon-intensive production to countries with weaker environmental regulations, rather than reducing global emissions overall. If a committed country raises its carbon price and emissions fall domestically, but a non-committed country increases production (and emissions) to fill the gap, the net climate benefit is minimal. CBAM addresses this by ensuring that the carbon cost embedded in imported goods is equivalent to the carbon cost of producing the same goods within the EU. It is designed to be compatible with World Trade Organization rules.²

The Engine Behind CBAM: The EU Emissions Trading System

To understand CBAM, it helps to understand the EU Emissions Trading System (EU ETS), the cap-and-trade carbon market that powers it. Under the EU ETS, the EU sets a declining overall cap on emissions and issues allowances — each allowance representing one metric ton of CO₂. Allowances enter the system primarily through government auctions, with some free allocation to certain trade-exposed sectors. Companies and financial participants then trade these allowances in a carbon market, and the market price of those allowances becomes the EU's effective carbon price.³

CBAM uses this same carbon price to determine what importers must pay. Each year, the EU importer, not the foreign producer, is legally responsible for CBAM compliance. That means the importer must collect embedded emissions data from its foreign supplier, report those emissions to EU authorities, purchase CBAM certificates based on the reported emissions, and surrender certificates equal to the total embedded emissions. Excess certificates can be resold on a secondary market for the current carbon price.  Certificate prices are tied to EU ETS allowance prices: specifically, the quarterly average ETS price in 2026, shifting to a weekly average starting in 2027.⁴

To make this concrete: if an EU steel plant emits 100,000 tons of CO₂ and the ETS price is €75 per ton, it faces a carbon cost of €7.5 million. If that same company also imports steel with 10,000 tons of embedded CO₂, it must purchase 10,000 CBAM certificates at €75 per ton — a CBAM cost of €750,000. If the ETS price subsequently rises to €80 per ton, that same import obligation would cost €800,000. The mechanism ensures the carbon cost is applied equally to domestic and imported production.⁴

Who Is in Scope?

The CBAM regime began on January 1, 2026. The initial sectors covered are cement, iron and steel, aluminum, fertilizers, electricity, and hydrogen, but the scope does not apply to entire industry categories. Instead, product classification codes, or Combined Nomenclature (CN) codes defined in the CBAM regulation’s annexes determine which products industries must purchase certificates for.⁵

Importers bringing more than 50 tonnes of CBAM-covered goods into the EU must be registered as authorized CBAM declarants and purchase certificates from national authorities. Notably, non-EU exporters who are not directly subject to EU law can still be pulled into what might be called "commercial scope": the EU importer has a legal obligation to report emissions, which means it needs emissions data from its supplier, which means the supplier becomes commercially subject to CBAM requirements even without a direct legal obligation.⁵

The Emissions Data Challenge

CBAM compliance is fundamentally a data problem. For each covered import, the EU importer must report facility-level production emissions, indirect emissions from electricity where required, and the calculation methodology used. The EU importer bears the legal obligation, but the actual data can only come from the foreign supplier.⁶

This creates a significant operational dependency. If a supplier cannot provide verified emissions data, the importer is required to fall back on default values established by the European Commission.⁷ These default values are intentionally conservative — set high to incentivize actual data collection — meaning that reliance on them carries a higher implied carbon cost and can place an importer at a competitive disadvantage.⁸

The practical effect is that emissions data has become a commercial input, not merely a sustainability metric. A supplier's ability or inability to provide verified facility-level data directly affects the importer's compliance costs, pricing, and sourcing decisions.

Implications Across the Supply Chain

CBAM creates different pressures depending on where a company sits in the supply chain.

For EU importers, the stakes are straightforward: legal obligation, financial exposure tied to the ETS carbon price, and the operational challenge of gathering reliable data from potentially dozens of foreign suppliers. Companies will likely need cross-functional ownership spanning customs and trade, finance, legal, environmental health and safety, and sustainability reporting.¹

For non-EU suppliers, there is no direct legal requirement, but the commercial implications are real. Suppliers who cannot provide verified low-emissions data risk being replaced by competitors who can, or may face pricing pressure as importers seek to offset the cost of purchasing certificates at default values. Conversely, suppliers with verified low-emissions production can differentiate themselves and potentially command a pricing premium. A supplier's competitive position in the EU market will increasingly depend on its emissions performance and its ability to document it.⁵

For companies throughout carbon-intensive supply chains, embedded emissions now translate directly into certificate costs, creating margin pressure — particularly in commodity sectors where margins are already thin.¹ The CBAM framework effectively extends the EU's carbon price signal far beyond EU borders, reshaping sourcing decisions and supplier relationships in ways that are only beginning to be felt.