ESRS E1 GHG inventory requirements: CSRD after Omnibus

1Precisely what the CSRD requires

The CSRD (Corporate Sustainability Reporting Directive) is the EU directive updating and extending non-financial reporting in Europe. It replaces the previous Non-Financial Reporting Directive (NFRD), and the non-financial performance statement (DPEF) under French law, with much more precise requirements and an initially very broad scope that Omnibus narrowed to the largest companies.

CSRD reporting centres on the ESRS (European Sustainability Reporting Standards), a set of standards published by EFRAG (the European Financial Reporting Advisory Group). ESRS E1, which addresses climate change, requires the greatest amount of quantitative data. To comply, a company must publish, among other things:

• Its full greenhouse gas (GHG) inventory for Scope 1, Scope 2 (both location-based and market-based methods) and Scope 3 for material categories (in French) (the sources that make a real difference)
• Its reduction targets, if it has set any, stating whether they are compatible with a 1.5°C pathway
• Its climate transition plan (in French) with actions, a timetable and allocated resources, if it has one (otherwise, it states whether and when it intends to adopt one)
• The climate risks and opportunities associated with its activities (physical and transition risks)
• The expenditure and investments associated with the transition

All these data require a sound greenhouse gas inventory as their starting point. Physical risks are assessed using knowledge of the geographical areas of exposure, but a reduction pathway can only be built on a full Bilan Carbone® (the French carbon accounting method): otherwise, the company does not even know what it needs to reduce.

2Who is in scope in 2026

The CSRD's scope in 2026:

• Large listed companies with more than 500 employees (and equivalent entities: banks and insurers), reporting since the 2024 financial year; those not exceeding both 1,000 employees and €450 million turnover leave the scope once Omnibus is transposed, and the directive allows Member States to exempt them from reporting for the 2025 and 2026 financial years
• Other large companies with more than 1,000 employees and €450 million turnover, from the 2027 financial year (the stop-the-clock Directive's postponement and Omnibus thresholds)
• No more listed small and medium-sized enterprises (SMEs): Omnibus removed them from the framework
• Indirectly, all SME subcontractors to these companies, through cascading pressure for Scope 3 data

The regulatory framework has changed since 2024. In early 2025, the European Commission proposed an Omnibus package, which became Directive (EU) 2026/470, published on 26 February 2026: once transposed, by 19 March 2027 at the latest, it restricts the CSRD to companies with more than 1,000 employees and €450 million turnover. Despite these adjustments, the central principle remains: once a company is in CSRD scope, Bilan Carbone® including Scope 3 becomes fundamental.

To determine precisely whether your company is covered and in which wave, consulting your statutory auditor or a specialist firm directly remains the most reliable approach: threshold effects and exemptions have changed considerably over the last 18 months.

3The CSRD sequence, step by step

For a French mid-cap company (ETI in French) entering CSRD scope, the process looks like this:

Materiality assessment. The first exercise to undertake, often before Bilan Carbone®. It identifies the environmental, social and governance issues material to the company, meaning those that matter to its stakeholders and business model. Climate is found to be material in almost every case.

Full Bilan Carbone® covering Scopes 1 + 2 + material Scope 3. This is the central element of climate reporting. It must be produced using a recognised method, with sufficient data traceability to withstand external scrutiny (the CSRD requires verification by an independent third party, with limited assurance).

Climate transition plan. Using the assessment, the company builds its decarbonisation pathway with milestones (typically 2030 and 2050), quantified actions and human and financial resources. ESRS E1 requires it to explain how its targets are compatible with limiting warming to 1.5°C.

Annual reporting. Each year, the greenhouse gas inventory is updated, progress is measured and the data are incorporated into the sustainability statement. This is an ongoing obligation rather than a one-off exercise.

4What it costs in 2026

Indicative budgets for a mid-cap company with more than 1,000 employees entering CSRD scope:

• Materiality assessment: €15,000 to €40,000 excl. VAT, depending on complexity
• First full Bilan Carbone®: €20,000 to €50,000 excl. VAT, depending on the number of sites, supply chain complexity and international scope
• Climate transition plan and roadmap: €10,000 to €30,000 excl. VAT
• Annual updates: €8,000 to €25,000 excl. VAT per year
• External verification (progressive): €10,000 to €30,000 excl. VAT per year

Total budget for a mid-cap company entering CSRD scope: typically €50,000 to €150,000 excl. VAT in the first year, with recurring annual costs of €25,000 to €60,000 excl. VAT. For large groups, budgets can exceed €500,000 excl. VAT per year.

For SME subcontractors that must provide data to clients subject to the CSRD, there is good news: they can often use Diag Décarbon'Action (a carbon footprint programme for companies established in France, subsidised by Bpifrance, the French public investment bank) for their own assessment, with a company contribution of around €6,000 excl. VAT.

5The three pitfalls to avoid

Pitfall 1: waiting until the last minute. The CSRD requires mature data collection and traceability processes that cannot be improvised. A company waiting until 6 months before its first publication to start Bilan Carbone® faces a crisis, with costs rising by 30 to 50% and an unreliable deliverable. Last year, we took over a project for an industrial mid-cap company with 800 employees that had waited until 5 months before its first statement: an urgent full Bilan Carbone® costing €48,000 excl. VAT (compared with €32,000 excl. VAT under normal conditions), six weekends of data collection for the corporate social responsibility (CSR) team and a formal qualification by the statutory auditor concerning the traceability of Scope 3 category 1 (purchased goods) data. Companies that managed the process well started 18 to 24 months before the deadline.

Pitfall 2: treating Bilan Carbone® as a compliance deliverable. The CSRD assessment is a tool for managing a climate strategy, rather than a box to tick for the regulator. Companies treating it purely as reporting end up with a cosmetic (in French) action plan that will withstand neither the first substantive scrutiny nor investors' analysis.

Pitfall 3: outsourcing everything to the financial auditor. Statutory auditors will verify the data, but they will not produce them. Bilan Carbone® is the work of a climate consultancy rather than an audit firm. Confusing the two roles often leads to a poorly scoped engagement and difficult discussions during the review. Our CSRD climate reporting support organises emissions data, methodological documentation and the transition plan elements to prepare for review.

6What to agree before the first publication

The CSRD timetable works backwards from publication, and it is tight. 24 months before: start the materiality assessment, the first filter determining everything that follows. 18 months before: a full Bilan Carbone® covering Scopes 1, 2 and material Scope 3, without which ESRS E1 is unattainable. 12 months before: a transition plan aligned with the 1.5°C pathway where material. 6 months before: statutory auditor review and third-party verification. Any company entering this timetable late pays 30 to 50% more: compressed deadlines, weekends for the CSR team and formal qualifications by the statutory auditor. Delay, rather than the requirement itself, sends the bill soaring.

The strategic approach we recommend to all our mid-cap clients: treat the CSRD as a climate management tool, rather than a regulatory deliverable. A company building Bilan Carbone® to decarbonise effectively also achieves impeccable CSRD compliance as a result. The reverse does not hold.

Further resources

Frequently asked questions

1Is Bilan Carbone® mandatory under the CSRD?

The directive does not name Bilan Carbone®, but ESRS E1, the CSRD's climate standard, makes an emissions inventory essential. It requires publication of Scope 1 and 2 emissions (location-based and market-based) and Scope 3 emissions for material categories, climate risks and reduction targets and the transition plan if they exist (otherwise, the company states whether and when it intends to adopt them). These data cannot be produced without a structured assessment using a recognised method, with sufficient traceability to withstand verification by an independent third party.

2How detailed must Scope 3 reporting be under the CSRD?

ESRS E1 requires Scope 3 for material categories, meaning the sources that make a real difference to your emissions among the Greenhouse Gas Protocol's (GHG Protocol) 15 categories, and exclusions must be justified. The expected depth mainly concerns traceability: the data must withstand external verification. For major sources such as purchased goods (category 1), overly crude ratios based on spending expose the company to a qualification by its statutory auditor. To meet this requirement, it is better to start the assessment around 18 months before the first publication.

3Is a Bilan Carbone® audit mandatory under the CSRD?

Yes, sustainability information published under the CSRD, including the emissions inventory, must be verified by an independent third party: in France, a statutory auditor or an accredited independent third-party body. This is limited assurance, as the Omnibus I Directive, published in February 2026, removed the planned progression to reasonable assurance. Allow €10,000 to €30,000 excl. VAT per year for this verification in a mid-cap company. Producing the data remains the responsibility of the company and its climate consultancy, with the auditor subsequently verifying them.

4What does a CSRD-compatible Bilan Carbone® cost?

For a mid-cap company with more than 1,000 employees, a first full Bilan Carbone® costs €20,000 to €50,000 excl. VAT, depending on the number of sites, supply chain and international scope. It forms part of an initial budget of €50,000 to €150,000 excl. VAT in the first year, including the materiality assessment (€15,000 to €40,000), transition plan (€10,000 to €30,000) and external verification (€10,000 to €30,000 per year). Recurring costs then run at around €25,000 to €60,000 excl. VAT per year. An assessment started under urgent conditions costs 30 to 50% more.

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