CBAM Supplier Data Requirements: What EU Importers Need

If you sell bolts and nuts, steel coil or aluminium into the EU, you may have had an email like this. It comes with an Excel form and asks for two things:

• embedded emissions: the amount of carbon released in making the goods
• verification report: a document from an accredited body confirming that number is right

The reason is the EU's Carbon Border Adjustment Mechanism, or CBAM. Since 1 January 2026, CBAM is in the stage where importers actually pay.^[1] It covers six kinds of goods: iron and steel, aluminium, cement, fertilisers, hydrogen and electricity.^[1]

From 2026, an EU importer needs EU authorisation to bring these goods in. Companies that import 50 tonnes or less a year are left out. Hydrogen and electricity are not left out, however small the amount.^[1] If the declaration is wrong, the declarant alone is responsible. That is usually the importer, in other words your customer.^[1] Your customer carries the responsibility, but the numbers sit in your plant. That is why they are asking you.

The importer declares the carbon in its goods using one of two kinds of numbers.^[1]

① Measured numbers (actual values)

Your plant measures its own carbon and has it checked by an EU-accredited verifier.^[1][2] Without that check document (the verification report), these numbers can't be used.

② Numbers set by the EU (default values)

These are used when there are no actual values. The EU has set them in tables, by country and by year.^[1][3] If your country or product isn't in the table, the "other countries" figure applies.^[1] Default values are set high on purpose, so they don't come out lower than reality. An extra charge (a mark-up) is added on top: 10% in 2026, 20% in 2027 and 30% from 2028.^[1] So declaring on default values usually costs more. The EU itself says actual values are usually the better option where you have them.^[1]

Worth knowing

What counts is the year the goods entered the EU. For goods that entered in 2026, only numbers measured over 2026 can be used. This holds even if the goods were made in 2025. Numbers measured before 2026 can't stand in.^[1]

How different is the cost on default values vs actual values? (hypothetical example)

This is a made-up example to help explain. The actual value and the tonnage are assumptions.

• Say a Korean plant shipped 100 tonnes of bolts (7318 15) to the EU in 2026.
• Default value: 3.474 plus the 10% mark-up is about 3.82 tonnes of carbon per tonne.^[14][1]
• Actual value: assume the plant measured 2.0 tonnes per tonne.
• Difference: about 1.82 tonnes per tonne, or about 182 tonnes for 100 tonnes of bolts.
• At the Q3 certificate price of €82.32, that is about €15,000.^[13]
• In 2027 the mark-up is 20%, so the gap grows to about €18,000, assuming the same price.

This example compares the difference in carbon only. The actual bill is set after the free allowances are taken off.^[1] How much is taken off also depends on whether actual or default values are used, so the example leaves it out.^[1]

The EU has written out the preparation steps in its guide for plants outside the EU.^[4] The key is to first write down what you will measure and how. This document is called the monitoring plan.^[4] Verifiers look at this plan when they do their check.^[4]

1. 01
   Set the scope: the plant's boundary, the goods it makes and how it makes them (the production route).^[4]
2. 02
   Set the period: measure in one-year blocks, January to December.^[4]
3. 03
   Choose what to measure: fuels burned, input materials (precursors) and the amount of goods produced.^[4]
4. 04
   Choose how to measure: read it from meters, or calculate it from purchase records and stock.^[4]

   • For the carbon content of fuels, use official national standard values or a lab analysis.^[4]
5. 05
   Keep the data for the free allowance calculation: it is needed to work out what the plant would have received if it were in the EU.^[4]
6. 06
   Set up checks against mistakes: assess where data could go wrong, and decide how to double-check it.^[4]
7. 07
   Measure for a year, then calculate at year-end: add up the year and work out the carbon per tonne of product.^[4]
8. 08
   Send it in the set format: give it to your customer in the EU's common English form (the operator's emissions report).^[4]

You can also register your plant in the EU's online system.

For now it's optional, but the EU strongly recommends it.^[4] Once you upload your data, you can share it with several customers.^[4] Customers only see a summary, so your confidential details stay protected.^[4] If you don't register, you have to send documents to each customer separately.^[4]

• The plant that makes the goods (the producer) gets it. The producer hires the verifier directly. If the producer doesn't, the customer declares on default values.^[1]
• Each plant is checked separately. One plant gets one verification report, in English. For the first check, the verifier visits the plant in person.^[1][2]
• Verifiers are only just being approved. National accreditation bodies started assessing verifiers in April 2026.^[2]
• Where things stand in October 2026:^[15][2]

  • 24 national accreditation bodies have agreed to accredit CBAM verifiers.^[15]
  • 7 of them already accept applications from verifiers outside the EU.^[15]
  • They are in France, Greece, Italy, the Netherlands, Poland, Slovakia and Sweden.^[15]
  • The EU page where the list of accredited verifiers will be posted has no list yet (checked 28 Oct 2026).^[2]
  • Sweden's accreditation body has announced its first accredited CBAM verifier.^[16]
• Verifiers from outside the EU have one more step. Their own country's accreditation body must first work with an EU accreditation body before the assessment can start (per Sweden's accreditation body).^[16]
• The first verification reports come out in January 2027.^[2]
• Watch out for this kind of offer. The EU warns that if anyone other than the plant offers to sell you a verification report, it may be a scam.^[1]

• Bolts and nuts are already covered. Product code (CN code) 7318, meaning iron or steel screws, bolts, nuts and washers, is covered by CBAM.^[5]
• The product code decides. Even if other materials are attached, the goods are covered if the code is. Only the iron or steel part counts for carbon.^[1]
• You don't need to send electricity use. For steel and aluminium, only the carbon from fuel burned at the plant counts. Carbon from electricity use counts only for cement and fertilisers.^[1]
• Which processes count is fixed.^[1]

  • Included: reheating, rolling, forging, pickling (cleaning with acid), annealing (softening with heat), coating, galvanising, wire drawing
  • Excluded: plating, cutting, welding, finishing
• The carbon of your input materials is added. Carbon released in making the iron or steel you buy in (precursors) counts too.^[1]
• You can mix. Input materials can go on default values while your own process uses actual values.^[1]
• You have to get input material numbers directly. Companies can only exchange these numbers through the EU online system (the CBAM Registry) from 2028. Until then, get them directly from your material supplier.^[1]

1. 01
   Carbon numbers can enter price talks. Your customer's CBAM cost depends on the numbers you send. Actual values can lower that cost. If you stay on default values, your customer may ask for a lower price. So settle your own approach before your next price discussion with the customer.
2. 02
   The burden grows every year. The mark-up rises from 10% to 30%. Free allowances for EU plants shrink until 2034.^[1] The Korea International Trade Association (KITA) ran a calculation through 2034, based on a set of assumptions.^[11] It found that prices of Korean exports to the EU could rise by up to 18.2%, and export volumes could fall by up to 17.9%. So this isn't a one-off job for this year. Plan to handle it every year.
3. 03
   Steel has the most at stake. KITA published an analysis in 2023.^[10] Of Korea's CBAM-covered exports to the EU, 89.3% were steel and 10.6% aluminium. This isn't only about large steelmakers. Processed goods such as bolts and nuts are covered directly, depending on their product code.^[5] First check whether your product code is covered.
4. 04
   You need to decide this year. 2026 imports can only be declared with numbers measured over 2026. To declare 2027 imports on actual values, you need to start measuring in January 2027. Before that, you need a monitoring plan. The steps are in "How does a plant start measuring its carbon?" above.^[4] There aren't many verifiers yet either. Only 7 accreditation bodies accept applications from outside the EU.^[15] Before the year ends, decide: "measure and get verified, or stay on default values". Then tell your customer.

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