The Carbon Border Adjustment Mechanism (Calculation of CBAM Rate and Determination of Carbon Price Relief) Regulations 2026

The Carbon Border Adjustment Mechanism (Calculation of CBAM Rate and Determination of Carbon Price Relief) Regulations 2026, enacted under Part 5 of the Finance Act 2026, establish the detailed framework for calculating the UK's new carbon border tax. These Regulations, set to come into force on 1 January 2027, are crucial for businesses importing carbon-intensive goods into the UK. They specify how the CBAM rate will be determined, primarily by referencing the UK Emissions Trading Scheme (UK ETS) and accounting for free allowances. Furthermore, the Regulations outline the conditions and methodology for claiming carbon price relief, allowing importers to deduct explicit carbon prices already paid in the country of origin. This article examines the practical implications of these provisions for legal practitioners and affected industries, highlighting the complexities of compliance and the need for robust data management.

The United Kingdom's commitment to achieving net-zero emissions by 2050 has led to the introduction of a comprehensive carbon pricing architecture. A significant component of this framework is the Carbon Border Adjustment Mechanism (CBAM), a new tax designed to prevent 'carbon leakage' – the relocation of carbon-intensive production to countries with less stringent climate policies. The primary legislative basis for this mechanism is found in Part 5 of the Finance Act 2026, which establishes the charge to CBAM. Building upon this, The Carbon Border Adjustment Mechanism (Calculation of CBAM Rate and Determination of Carbon Price Relief) Regulations 2026 (the “Regulations”) provide the essential secondary legislation, detailing the operational mechanics of this pivotal environmental tax.

These Regulations, which will take effect from 1 January 2027, are critical for any business involved in importing specified carbon-intensive goods into the UK. They clarify the intricate process of calculating the CBAM rate, which directly impacts the tax liability, and lay down the conditions for claiming carbon price relief, a vital mechanism to avoid double taxation where a carbon price has already been paid overseas. This article will delve into the provisions of these Regulations, analysing their practical implications for legal professionals advising clients on compliance, supply chain adjustments, and strategic planning in the face of this new regulatory landscape.

The UK CBAM is a direct response to the risk of carbon leakage, aiming to ensure that imported carbon-intensive products face a comparable carbon price to those produced domestically under the UK Emissions Trading Scheme (UK ETS). The UK ETS, operational since January 2021, is a cap-and-trade system that applies a cost to greenhouse gas emissions from power generation, energy-intensive industries, and aviation. Domestic producers within these sectors incur a carbon cost through the UK ETS, and the CBAM seeks to level the playing field for imports.

Part 5 of the Finance Act 2026 introduces CBAM as a tax, to be administered by His Majesty's Revenue and Customs (HMRC). It applies to imports of goods in five designated sectors: aluminium, cement, fertilisers, hydrogen, and iron and steel. Notably, electricity imports are excluded from the UK CBAM, a distinction from the European Union's CBAM. The Regulations are made under powers conferred by sections 145(2), 146(5), 147(2), and 154(2) of the Finance Act 2026, providing the necessary detail for the calculation of the CBAM rate and the determination of carbon price relief.

The Regulations are instrumental in operationalising the UK CBAM by providing clarity on two core aspects: the calculation of the CBAM rate and the determination of carbon price relief. Part 2 of the Regulations clarifies steps involved in calculating the sectoral domestic price, which is a key element of the CBAM rate as set out in section 146 of the Finance Act 2026. The CBAM rate itself is a single, sector-specific tax rate that will apply to the embedded emissions in imported goods, designed to reflect the 'effective carbon price' in the UK. This rate will be set quarterly by the government, primarily referencing the average auction price under the UK ETS for the preceding quarter.

A crucial adjustment in the CBAM rate calculation accounts for the allocation of Free Allowances (FAs) under the UK ETS. UK domestic producers in carbon-intensive sectors often receive FAs to mitigate carbon leakage risks, and the CBAM rate will be adjusted to reflect these, ensuring importers are charged on a comparable 'effective carbon price'. The Regulations specify that this FA adjustment will be based on a sectoral average of emissions covered by FAs over a baseline period, further adjusted annually by a 'reduction factor' to reflect the planned phase-out of FAs under the UK ETS. This intricate calculation necessitates a deep understanding of both the UK ETS mechanics and the specific provisions of these Regulations.

Part 3 of the Regulations addresses carbon price relief (CPR), a critical component for preventing double taxation. Section 150 of the Finance Act 2026 provides the power for regulations to reduce the CBAM charge if another monetary amount is payable in relation to the emissions, whether as taxation, in exchange for allowances under an emissions trading scheme, or as an import-related charge in the country of origin. The Regulations set out the conditions for claiming this relief and define what constitutes a 'qualifying carbon pricing scheme'. CPR is calculated by multiplying the relevant imported embodied emissions by the effective carbon price already paid overseas. Importers seeking relief must provide verified evidence of any carbon price deductions claimed, including for their supply chain, even if they did not produce the goods themselves. This places a significant burden on importers to gather and verify granular data from their international suppliers.

The administrative burden on importers is substantial. Businesses importing CBAM goods with a value of £50,000 or more over a rolling 12-month period must register with HMRC, keep detailed records, and submit periodic returns. The requirement for verified emissions data, or the use of government-set default values, further underscores the need for robust internal systems and potentially external verification. While the UK CBAM shares the objective of its EU counterpart, its operation as a tax, rather than a certificate purchase system, and differences in scope and implementation timelines, mean that businesses cannot simply transpose their EU CBAM compliance strategies to the UK context.

The Carbon Border Adjustment Mechanism (Calculation of CBAM Rate and Determination of Carbon Price Relief) Regulations 2026 represent a significant step in the UK's climate policy, translating the broad legislative intent of the Finance Act 2026 into actionable legal requirements. For practising attorneys, understanding these Regulations is paramount to effectively advise clients engaged in international trade of carbon-intensive goods. The complexities surrounding the calculation of the CBAM rate, particularly the adjustments for UK ETS free allowances, and the stringent requirements for claiming carbon price relief, demand meticulous attention to detail and robust data management strategies.

Practitioners should guide clients on establishing robust monitoring, reporting, and verification systems for embedded emissions and overseas carbon prices. Proactive engagement with supply chains to obtain necessary data will be crucial. As the UK CBAM comes into full effect from 1 January 2027, businesses must prepare for increased compliance costs and potential adjustments to procurement strategies. Legal professionals should closely monitor further guidance from HMRC and any future amendments to the Regulations, as the practical application of this new tax regime evolves.