CSRD and CBAM: How the Two Rules Interact After the Omnibus

If your company imports steel, aluminium, cement, fertilisers, hydrogen or electricity into the EU, it is now paying for the embedded CO₂ on every shipment above the de minimis threshold. The Carbon Border Adjustment Mechanism (CBAM) reached its definitive regime on 1 January 2026, and the first annual CBAM declarations covering calendar year 2026 are due in 2027 — the same window as your first revised-scope CSRD sustainability statement. Most groups touched by both are still running them as two separate programmes, with two separate workstreams, two sets of supplier questionnaires and two reconciliations against the same product bill of materials.

That is not the shape the regulation calls for. The Omnibus Simplification Package narrowed CSRD scope and trimmed CBAM's administrative burden on the long tail of small importers, but it did not change the fact that the two regimes share data, suppliers and governance. A group running them as one programme spends less, learns faster, and arrives at limited assurance with a cleaner evidence file.

This guide walks through what CBAM is, what the Omnibus actually changed, where CBAM overlaps with the CSRD and ESRS E1, where they diverge, and how to structure a CSRD engagement — and the consultant who runs it — to cover both at the same time.

What CBAM Is, in One Section

CBAM is Regulation (EU) 2023/956, the EU's carbon-price-at-the-border. Its purpose is to prevent "carbon leakage" — the risk that EU producers who pay for emissions under the EU ETS lose out to importers from jurisdictions with weaker carbon pricing — by charging importers for the embedded CO₂ in a defined list of carbon-intensive goods.

The covered product groups, as of the start of the definitive regime, are:

• Cement
• Iron and steel, including downstream products such as screws, bolts and certain fabricated items
• Aluminium, including primary metal and selected downstream products
• Fertilisers, including ammonia, nitric acid and compound fertilisers
• Hydrogen
• Electricity

Three obligations sit at the heart of the mechanism:

• Authorised CBAM declarant status — only an authorised declarant may import covered goods above the de minimis threshold. Status is granted by the member-state competent authority.
• Reporting of embedded emissions — the direct emissions from the production of each imported good, and for some product categories indirect emissions from the electricity used, measured per tonne of product under the methodology set out in the CBAM implementing regulations.
• Surrender of CBAM certificates — for every tonne of embedded CO₂ above the EU ETS free-allocation benchmark for that product category, the declarant buys a CBAM certificate at a price linked to the weekly EU ETS auction price and surrenders it to the authority in the following year.

Importantly, CBAM is a per-shipment, per-product obligation on the EU importer, not a company-wide disclosure. It attaches to goods at the EU border, not to the sustainability statement of the group that imports them.

What the Omnibus Changed for CBAM

Directive (EU) 2026/470 is the Omnibus directive that amended the CSRD, the CSDDD and the EU Taxonomy. CBAM itself sits in a separate regulation (Regulation (EU) 2023/956), and the Omnibus package included parallel amendments to it aimed at the same simplification objective. The direction of travel is clear in both instruments: focus the compliance effort on the companies and shipments that drive the material carbon-leakage risk, and spare the long tail.

Four changes matter for the CSRD programme:

1. Higher de minimis exemption

The Omnibus raised the de minimis threshold so that a large share of occasional and low-volume importers now fall outside the CBAM obligation. The policy intent was to focus the regime on the roughly 20% of importers who account for the overwhelming majority of embedded emissions. Check the current de minimis in the implementing regulation before concluding your flows are exempt, as transition and definitive-regime figures differ and are set by implementing act, not by the main regulation.

2. Simplified authorised declarant process for small importers

Smaller importers who remain in scope benefit from a lighter authorisation process, with reduced documentation and a simplified route to buy and surrender certificates. The substantive duty to report embedded emissions and surrender certificates is unchanged for in-scope importers.

3. Streamlined embedded-emissions methodology

The Omnibus accelerated the move away from the transitional-period default values towards verified actual emissions data for larger shipments, while allowing a simplified calculation route for low-complexity goods and small volumes. For CSRD programmes, that means the CBAM data your trade team collects on larger shipments is increasingly audit-grade product-level emissions data — exactly the input ESRS E1 wants for Scope 3 Category 1.

4. Scope and governance clarified

The product-category list was not expanded in the Omnibus beyond the categories already in the definitive regime; a review of possible extension to downstream products and additional sectors is in train but not yet legislated. For the next two reporting cycles, plan to the current list and treat extensions as a watch item in the group's regulatory horizon-scanning.

The Omnibus simplifications are administrative, not substantive: the carbon-pricing logic — pay at the border for embedded CO₂ above the ETS free-allocation benchmark — is intact.

Where CSRD and CBAM Overlap

Four overlaps are big enough that an experienced consultant will design them to share a single workstream.

Embedded emissions and Scope 3 Category 1

The clearest overlap. CBAM embedded emissions, measured per tonne of imported product, are a direct input to your ESRS E1 Scope 3 inventory, specifically Category 1 (Purchased goods and services) for the covered product groups. A group that imports significant volumes of steel, aluminium or cement will find that CBAM-grade data on those products is more accurate than GHG Protocol default spend-based factors.

Methodology differs — CBAM uses its own system boundaries and defaults for product-level emissions; the GHG Protocol allows a wider set of calculation methods — so the two numbers rarely reconcile line-for-line. The practical answer is a disclosed reconciliation: use CBAM data for the covered categories, keep the GHG Protocol methodology for the rest, and document the bridge in the sustainability statement.

Supplier data and the value chain

Both regimes need structured data about upstream suppliers of carbon-intensive inputs: supplier identity, country of origin, production route, electricity source and embedded emissions per tonne. For CBAM this feeds the quarterly reports in the transitional phase and the annual declarations in the definitive regime. For CSRD, the same data feeds ESRS E1 Scope 3, parts of ESRS E2 (pollution), and value-chain reporting under the ESRS 2 cross-cutting standards.

Running one supplier survey, one data pipeline and one request cadence for both reduces supplier fatigue and keeps the number consistent between the CBAM declaration and the Scope 3 inventory.

Transition plans and decarbonisation of carbon-intensive inputs

The ESRS E1-1 climate transition plan requires named decarbonisation levers consistent with limiting warming to 1.5°C. For an industrial group with material CBAM exposure, the levers most likely to appear in that plan — switching to lower-carbon steel or aluminium suppliers, substituting cement with lower-clinker alternatives, electrifying hydrogen inputs — are the same levers that reduce CBAM certificate exposure. The plan and the CBAM strategy are one document, not two.

Governance, controls and the audit trail

Both regimes expect board-level oversight of the carbon-footprint data, documented methodology, and an audit trail that connects raw supplier data to the final declared or disclosed figure. The CSRD's limited assurance opinion covers the ESRS E1 Scope 3 figures. CBAM declarations are verified by accredited verifiers under the CBAM regulation's own verification regime. A single data governance structure — one data owner, one methodology document, one evidence file — serves both.

Where They Diverge

Four divergences matter enough that treating the two as the same creates a programme risk.

Who it applies to

CBAM attaches to the EU importer of record on a per-shipment basis. CSRD attaches to the EU-registered group or qualifying non-EU parent on an annual basis. The CBAM declarant is often a trading entity or a procurement subsidiary; the CSRD reporter is the parent that consolidates the sustainability statement. A single corporate map should show both, and they are not always the same legal entity.

Carbon pricing vs. disclosure

CBAM is a carbon-pricing mechanism: embedded emissions above the free-allocation benchmark cost money, and the price is linked to the EU ETS. CSRD is a reporting rule: ESRS E1 disclosures do not themselves cost per tonne of CO₂, though they do carry assurance and reputational consequences. A reduction in Scope 3 that does not cover CBAM-covered products saves no CBAM certificates. A reduction in CBAM certificate purchases that does not flow through to the ESRS E1 inventory saves no disclosure finding.

Methodology and defaults

CBAM uses its own definitions of direct and indirect emissions, its own system boundaries by product category, and its own fallback default values (particularly during transition and for low-complexity goods). The GHG Protocol — the methodology ESRS E1 points to — allows wider methods and more flexibility on defaults. The two numbers for the same shipment of steel will usually differ. Explain the difference once, in the methodology section of the sustainability statement, rather than year after year under assurance questioning.

Enforcement and timing

CBAM certificate purchases are enforced through customs and the member-state competent authority: shortfalls trigger penalties set in Regulation (EU) 2023/956 and the implementing regulations, and in extreme cases loss of authorised declarant status. The CSRD is enforced through the audit opinion and the member-state oversight regime for statutory reporting — see our penalties and non-compliance guide. The clocks also run differently: CBAM is a per-shipment customs duty with an annual true-up; the CSRD is an annual report. A missed CBAM certificate purchase is a problem in weeks, not next March.

Running Both as One Programme

If you take only one thing from this guide, take this: do not run two programmes side by side. Design them as one, with shared data, shared governance and shared supplier engagement, and give the differences the specific airtime they need. In practice that means:

1. One governance structure. A single board sponsor for carbon data (CSRD disclosures and CBAM declarations), with named operational leads in sustainability, trade/customs and tax. The group CFO owns the number either way.
2. One supplier data model. Covered-product suppliers, country of origin, production route, electricity source and embedded emissions per tonne — collected once, in one system, consumed by both the CBAM declaration and the Scope 3 inventory. See our data collection and gap analysis guide for how to size the data effort.
3. One decarbonisation lever list. The levers that reduce CBAM certificate exposure — lower-carbon suppliers, substitute materials, electrification of upstream processes — are the levers that reduce ESRS E1 Scope 3 and strengthen the transition plan. Build one list, prioritise once, report twice.
4. One supplier engagement cadence. A single supplier questionnaire, calibrated to pull CBAM-grade per-tonne emissions data and the broader Scope 3 context for CSRD. One cascade of procurement clauses, not two.
5. One methodology document. Explain the differences between the CBAM methodology and the GHG Protocol once, with a reconciliation bridge, and reference it from both the CBAM compliance file and the sustainability statement.
6. One assurance and verification file. The CBAM verifier and the CSRD assurance provider will inspect different cuts of the same evidence. Build the file with both audiences in mind — see our pre-assurance guide for how to pressure-test the trail before the assurer arrives.
7. One financial view. CBAM certificate exposure is a line in the P&L and a hedging decision. CSRD disclosure of climate-related financial effects (ESRS E1-9) wants a quantitative range for the same exposure. Keep the finance team's internal estimate and the disclosed range consistent.

The right structure costs materially less than running two programmes, and it produces an evidence file that holds together under scrutiny from either side.

What to Look For in a CSRD Consultant Who Also Covers CBAM

If you are hiring, add these to the standard CSRD consultant screen:

• Named CBAM experience, not generic trade compliance. Ask for a worked example — a quarterly report during transition or a definitive-regime declaration they have supported — and expect them to name the product category and the supplier type.
• A customs or indirect-tax partner. Pure sustainability consultancies without a customs partner will miss the authorised-declarant mechanics and the certificate-purchase cadence. A CBAM programme needs both lenses.
• A reconciliation methodology between CBAM data and the GHG Protocol. If the consultant does not know the two methodologies produce different numbers for the same shipment, they are not ready for the question your assurer will ask.
• A view on the free-allocation benchmark and ETS price trajectory. CBAM certificate exposure is partly a hedging problem. A consultant who treats it as a disclosure problem will not help your treasury team scenario-plan.
• Experience with supplier engagement across tiers in the covered sectors. Steel, aluminium and cement supply chains are concentrated but opaque on carbon data. Running a single CBAM-ready supplier survey is procurement work, not a desk exercise.
• A clear position on the independence constraint. The firm advising on CBAM compliance should not also be your statutory sustainability assurance provider for the same cycle — the self-review threat applies here as cleanly as it does under CSRD. A CBAM verifier is a separate accreditation again and should not be confused with either.

A consultant who treats CBAM as a reporting workstream has missed the point: it is a per-tonne cost that reaches your customs flows and your P&L. A consultant who treats CSRD as the CBAM annual report has missed the point the other way: ESRS E1 asks for the full Scope 3 picture and a transition plan, not a reconciled copy of your import declarations.

Common Mistakes to Avoid

• Treating CBAM as a trade problem and CSRD as a sustainability problem. The data is the same. Siloed teams produce reconciliations your assurer and your competent authority both reject.
• Using CBAM numbers as your full Scope 3 Category 1. CBAM covers specific products at specific borders. The rest of your Scope 3 inventory is still your job, under GHG Protocol methodology, and your assurer will check.
• Running two supplier surveys. Response rates on the second survey collapse. Both the CBAM declaration and the Scope 3 inventory suffer.
• Letting the CBAM certificate price surprise finance. The CBAM price moves with the EU ETS. A climate-related financial effects disclosure under ESRS E1-9 that does not reflect that exposure is a disclosable weakness.
• Assuming the Omnibus de minimis exempts you. The de minimis threshold is set in the implementing regulation. Check your actual annual tonnage before concluding you are out of scope, and watch for policy adjustments between now and the first full declaration.
• Buying "CBAM readiness" as a bolt-on to a drafted sustainability statement. A late bolt-on produces a thin reconciliation and a brittle data model. Build both from the start.
• Forgetting indirect emissions where they apply. Some product categories require declaration of indirect emissions from electricity used in production. A supplier mix that looks clean on direct emissions can still carry significant indirect emissions. Check the methodology category by category.

Where This Leaves You

If your group imports steel, aluminium, cement, fertilisers, hydrogen or electricity into the EU and sits in CSRD scope, start from the assumption that CBAM and the CSRD belong in one programme, running on one data model, with one supplier engagement and one transition plan. The Omnibus made that framing easier by trimming CBAM's long-tail compliance burden and aligning the CSRD scope with the industrial groups most likely to carry material import flows — and the CSRD consultants who understood that from the start of the definitive regime are the ones delivering clean reports and clean declarations on the same budget.

If you are not yet certain which parts of your flows CBAM covers, where the data gaps are, or how to design the overlap with your ESRS E1 workstream, that is the shape of a first consulting engagement — short, scoped, and focused on the data model before you commit to the full report.

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