HM Revenue & Customs (HMRC) has published illustrative cement-sector costs and accompanying technical guidance ahead of the UK Carbon Border Adjustment Mechanism’s (CBAM) introduction on 1 January 2027.

The worked example, published on 16 October, gives a cement-sector rate of GBP8.78/tCO2e. Applying this to HMRC’s published default emissions values produces indicative charges of approximately GBP12.58/t of imported clinker and GBP12.07/t of non-white Portland cement, before any qualifying overseas carbon-price relief.

The calculation uses an average UK Emissions Trading Scheme allowance price of GBP58.15/tCO2e for July–September 2026, adjusted to reflect domestic producers’ free allocation and its planned phase-out.

HMRC emphasises that these figures are illustrative, rather than forecasts or confirmed tax rates. The applicable rate for January–March 2027 will be published before year-end, with subsequent rates updated quarterly.

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Alongside the cost guidance, HMRC published a 313-page technical guide covering emissions monitoring, reporting and verification for overseas producers, verifiers and UK importers. Technical feedback is invited until 13 November, with further updates possible before implementation.

Producers supplying actual emissions data must appoint an independent accredited verifier whose scope covers the relevant production processes. Verification generally requires a physical site visit, with a report or product-specific summary supplied to the importer as evidence.

Accreditation bodies must publish lists of their CBAM-accredited verifiers and certificates. Importers may use default values instead, but returns submitted on that basis cannot subsequently be amended to substitute actual emissions data.

The final cement-sector rate could differ as carbon prices change and the UK ETS Authority completes checks on the free-allocation data underlying the calculation.