CBAM for Builders' Merchants: Mixed Imports Guide

Builders merchants face a unique CBAM challenge: they import goods from multiple CBAM sectors — steel (reinforcing bar, mesh, structural sections), aluminium (flashings, gutters, window frames), cement (bagged cement, ready-mix inputs), and potentially fertiliser (bagged fertiliser for landscaping) and hydrogen. Each sector has its own reporting methodology, default values, and data requirements.

Unlike a steel importer who only needs to understand steel sector methodology, a builders merchant must maintain working knowledge of all five CBAM sectors simultaneously. This creates significant administrative complexity, especially for merchants with large product catalogues running to thousands of SKUs.

The CBAM threshold of £50,000 annual landed value applies to the aggregate of all CBAM-covered goods across all sectors. If your total imports of steel, aluminium, cement, and fertiliser together exceed this threshold, you are liable. You cannot rely on low volumes in any single sector to avoid liability — it is the combined value that matters.

The first step for any builders merchant is to sort your product catalogue by commodity code. Identify every imported product that falls under the CBAM-covered headings: 72 and 73 (iron and steel), 76 (aluminium), 25 (cement), 31 (fertiliser), and 28 (hydrogen). Many merchants discover that products they assumed were outside scope — such as aluminium flashing or cement-based repair mortars — are actually covered.

Use the first 4 digits of the CN code to determine the sector. For example: 7308 covers steel structures (lintels, joist hangers), 7604 covers aluminium profiles (flashings, trims), and 2523 covers cement. Some products may fall under headings you do not expect — for example, some cement-based renders fall under 2523, and some aluminium composite panels may fall under 7610.

Once sorted, group products by sector and by supply source. This allows you to send targeted data requests to each supplier type. Your steel supplier needs to provide steel-format emissions data; your aluminium extruder needs to provide aluminium-format data. The data request format differs by sector because the calculation methodology differs.

For builders merchants, an efficient data collection approach is essential. Start with your highest-volume CBAM products: these represent the bulk of your emissions liability and are where accurate data has the most impact. For each product, identify the country of origin, the production route (e.g., BF-BOF vs EAF for steel, hydro vs coal for aluminium), and the supplier's ability to provide verified emissions data.

For low-volume products where supplier data is difficult to obtain, you may rely on default values published by the UK government. However, defaults are typically set higher than the actual emissions of efficient producers, so using defaults will generally increase your CBAM liability compared to using verified supplier data. Prioritise obtaining data from your largest suppliers first to maximise the benefit.

Oremly's multi-sector importer module is designed for builders merchants. It accepts your full product catalogue, automatically maps products to CBAM sectors, identifies the data requirements for each sector, sends sector-appropriate data requests to suppliers, and consolidates reporting into a single CBAM return. This eliminates the need to manage five separate sector compliance processes.