Covered by Schedule 16
Six codes are listed under cement in the Table in Schedule 16: 2523 10, cement clinkers; 2523 21, white Portland cement; 2523 29, other Portland cement; 2523 30, aluminous cement; 2523 90, other hydraulic cements; and 2507 00 80, other kaolinic clays.
Outside the tax
Nothing else in chapter 25 is covered. Kaolin under any subheading of 2507 other than 2507 00 80 is outside, and gypsum, slag, fly ash and limestone filler are not CBAM goods.
Your business imports cement for a ready-mix plant or a builders' merchant, clinker for a grinding plant, or calcined clay for a cement or ceramics works. Cement differs from the other four sectors in one respect that runs through this page: the functional unit for most cement is the clinker it contains rather than the tonnes of cement, and the conversion from one to the other rests on a notice that existed only in draft on 13 September 2026.
The kaolinic clay entry catches businesses that are not cement importers. Code 2507 00 80 is an eight-digit subheading, so only goods classified there are caught. Table 1b of the System Boundaries Document maps it to the category calcined clay, which shows the purpose: calcined clay is a partial substitute for clinker in blended cements, and it is brought into the tax as the precursor it can be.
The system boundary
Table 1b maps the six codes to four categories: calcined clay, cement clinker, aluminous cement, and cement for 2523 21 00, 2523 29 00 and 2523 90 00. For every category the only relevant gas is carbon dioxide. Point 3.5 sets the boundary for clinker: the calcination of limestone and other carbonates in the raw materials, all kiln and non-kiln fuels, alternative raw materials and the materials used for flue gas scrubbing, with no precursors. The calcination line is the one that makes clinker what it is for this tax: the carbon dioxide driven out of limestone in the kiln is a process emission that no change of fuel removes.
Point 3.6 sets the boundary for cement: the grinding plant's own processes, where relevant for drying, with cement clinker and calcined clay as the precursors. A grinding plant that buys clinker and grinds it with gypsum and additions therefore has small direct emissions of its own and carries the clinker maker's intensity as its precursor. Point 3.4 covers calcined clay and point 3.7 aluminous cement, each with no precursors.
Clinker content is the figure to hold
The document provides that for 2523 10 00, 2523 21 00, 2523 29 00 and 2523 90 00 the tonnes of clinker contained in the goods constitute the functional unit, so a supplier's intensity is per tonne of clinker contained and not per tonne of cement. Regulation 5(4) and (5) of SI 2026/995 then apply a conversion equation set out in a Treasury notice to produce the intensity per tonne of the good as imported. As at 13 September 2026 no Treasury notice under regulation 5(5) had been published. HMRC's draft Emissions and Verification notice of 9 September 2026 contains conversion equations that multiply the intensity per tonne of clinker by the clinker content of the goods; the draft notice does not currently have force of law and is due to take effect when commenced on 1 January 2027.
The practical consequence is that a cement supplier must record two things that a steel supplier need not: the tonnes of clinker contained in each product it makes, and the clinker content of each product as shipped. A supplier that reports an intensity per tonne of cement without stating the clinker content has given a figure that cannot be checked against the regulation. A blended cement with a low clinker content carries a lower embodied emission per tonne than a pure Portland cement from the same kiln, and the conversion equation is how that difference reaches the tax.
Regulation 4 of SI 2026/802 fixes the weight as net of packing at the time of import, so bagged cement is declared net of the bags and the pallets. Carbon price relief applies where the kiln sits in a jurisdiction with a qualifying scheme and form CarbonVP1 can be obtained; a grinding plant that buys clinker from a kiln in another jurisdiction needs a separate effective carbon price for the clinker under regulation 12(3) of SI 2026/809.
Questions for a cement supplier
For a kiln: does the monitored intensity cover the calcination of carbonates as well as all fuels, alternative raw materials and scrubbing materials, and is it expressed per tonne of clinker. For a grinding plant: which kiln supplied the clinker, does it have verified data, and what was the clinker content of each product shipped. For any supplier of Portland or other hydraulic cement: what is the clinker content of each grade, and can it be evidenced. For a supplier of aluminous cement or calcined clay: is the intensity per tonne of product. For every supplier in a jurisdiction with a carbon price: can form CarbonVP1 be completed for the kiln.
The check to run
Take the twelve months of customs declarations for goods under heading 2523 and code 2507 00 80, sort them by eight-digit code, and set against each the category from Table 1b, the functional unit and the installation. Lines under 2523 10 00 need a kiln's figure per tonne of clinker. Lines under 2523 21 00, 2523 29 00 and 2523 90 00 need a figure per tonne of clinker contained, the clinker content of the product and the conversion equation, and until the equation is published those lines cannot be finalised. A business that has the clinker contents on file for every grade it imports will be able to finish the calculation on the day the notice appears. Chapter 25 of UK CBAM for Importers sets out the sector in full.