Key takeaways
- The CS3D directive (corporate due diligence duty) no longer targets, since Omnibus I, anything but European companies with more than 5,000 employees and 1.5 billion euros in turnover: almost all Belgian SMEs fall outside its direct scope.
- Omnibus I, in force since 18 March 2026, pushes back the Member States' transposition deadline to 26 July 2028 and the application date for in-scope companies to 26 July 2029.
- The concrete effect for a Belgian SME is not a law to apply, but contractual requests from its large clients subject to the directive, who are already collecting information on their supply chain.
- Omnibus I caps these requests: a large company may only demand reasonable, proportionate information from a business partner that is not already available otherwise.
- Belgium has not yet transposed CS3D: no national obligation exists today, but the European timeline already shapes how large groups organise their procurement.
The CS3D directive (Corporate Sustainability Due Diligence Directive, also known as CSDDD) requires certain large European companies to monitor the impact of their activities and their supply chain on human rights and the environment. The original text, adopted in 2024, worried a share of Belgian SMEs who feared falling directly within its scope. Omnibus I, the simplification package published in the Official Journal of the European Union on 26 February 2026, changed the picture by sharply raising the application thresholds. This article sets out what remains and what disappears for a Belgian SME.
Who is actually covered by CS3D after Omnibus I
The original version of CS3D set the threshold at 1,000 employees and 450 million euros in worldwide net turnover for European companies, with a 450 million euro threshold on turnover generated in the Union for third-country companies. Omnibus I raised these thresholds to 5,000 employees and 1.5 billion euros in net turnover for European companies, and to 1.5 billion euros in turnover generated in the Union for third-country companies.
This increase radically changes the scope: a Belgian SME, even one of significant size at national level, sits very far from these thresholds. Only very large Belgian groups and the Belgian subsidiaries of multinationals of a size comparable to a large listed group can, in theory, be directly covered.
employees
new threshold (up from 1,000 originally)
net turnover
new threshold (up from €450m originally)
application date
for in-scope companies
Timeline: entry into force, transposition, application
Omnibus I entered into force on 18 March 2026, twenty days after its publication in the Official Journal of the European Union. This entry into force does not, however, make any obligation immediately applicable to companies: a directive must first be transposed into national law before it produces effects on the ground.
- 1
Publication of Omnibus I
26 February 2026Publication in the Official Journal of the European Union of the text that raises the CS3D thresholds and amends several of its obligations.
- 2
Entry into force
18 March 2026Omnibus I enters into force twenty days after its publication, which triggers the transposition deadline for Member States.
- 3
CS3D transposition deadline
By 26 July 2028 at the latestMember States, including Belgium, must have transposed the new CS3D rules into their national law.
- 4
Application to in-scope companies
From 26 July 2029Companies exceeding the new thresholds must comply with the due diligence obligations.
To date, Belgium has not yet adopted a law transposing CS3D. The large Belgian companies likely to fall within the scope of the directive are nonetheless already following the European Commission's preparatory work, whose implementation guidelines are expected in 2027.
Why a Belgian SME is still concerned in practice
The raised thresholds remove almost all Belgian SMEs from the direct scope of CS3D, but they do not shield them from every effect. The directive requires covered large companies to assess the adverse impacts of their chain of activities, which includes their suppliers and subcontractors, whether large or small themselves.
In practice, a Belgian SME that supplies goods or services to a large European group or to the Belgian subsidiary of a multinational may already receive, or receive in the future, a compliance questionnaire, a due diligence contract clause, or a request for information on its own social and environmental practices. It is not Belgian law that requires this: it is the client, meeting its own obligation.
The safeguards Omnibus I introduces for business partners
The original text of CS3D did not precisely limit the volume of information a large company could request from its suppliers, which raised fears of a disproportionate compliance burden being shifted onto SMEs in the value chain. Omnibus I introduces a framework for these requests.
| Before Omnibus I | After Omnibus I | |
|---|---|---|
| Depth of in-depth assessment | Entire chain of activities | Focused on direct business partners |
| Information that can be requested from a supplier | Not precisely framed | Limited to reasonable, proportionate information not obtainable otherwise |
| Obligation to adopt a climate transition plan | ||
| Civil liability regime | Harmonised at European level | Left to the national law of each Member State |
A large company subject to CS3D can therefore, in principle, no longer demand from an SME supplier information it could obtain by other means, nor multiply requests beyond what is necessary to identify the risks genuinely relevant to the business relationship concerned.
Anticipate your large clients' compliance requirements
Monsiegesocial helps Belgian SMEs structure their company and governance, including in response to compliance requests from their business partners.
What a Belgian SME can do right now
Without waiting for a Belgian transposition that is still to come, an SME that supplies goods or services to large groups has an interest in preparing, especially if its client belongs to a sector already sensitive to human rights or environmental issues (textiles, raw materials, food, construction).
Preparing for a CS3D cascade effect
Identify the large clients concerned
Spot, among your clients, those exceeding or approaching 5,000 employees and 1.5 billion euros in turnover, or Belgian subsidiaries of international groups of that size.
Document existing practices
Gather what already exists (supplier policy, certifications, quality controls) rather than building a compliance file from scratch at the first request.
Review proposed contractual clauses
Check that a due diligence clause inserted by a client stays proportionate and does not impose obligations beyond what Omnibus I allows a business partner to be asked for.
Follow the Belgian transposition
The Belgian transposition law, expected before 26 July 2028, will clarify the concrete rules applicable to Belgian companies falling within the direct scope of the directive.
The CSRD directive on sustainability reporting follows a comparable cascade logic for non-listed SMEs, with its own timeline and thresholds: see CSRD in Belgium: sustainability report, thresholds and 2026 timeline.
Going further
- CSRD in Belgium: sustainability report, thresholds and 2026 timeline : a neighbouring directive, with a distinct application timeline
- GDPR for SMEs in Belgium: obligations and penalties : another European compliance obligation transposed into Belgian law
- European Commission, corporate sustainability due diligence : official page tracking the CS3D file
