Subcontracting Chains in European Construction: Legal Risks Every Contractor Must Know

Multi-tier subcontracting is the structural reality of European construction. On any significant project — a new residential development in Brussels, a commercial fit-out in Munich, a motorway services refurbishment in Lyon — there will typically be a main contractor engaged by the client, multiple specialist subcontractors engaged by the main contractor, and potentially sub-subcontractors below them. Each link in this chain creates legal relationships and risks: liability for defects, liability for unpaid payroll taxes, direct payment rights that bypass the main contractor, and documentation requirements. These risks differ significantly by country, and a contractor who understands the Belgian framework may be poorly prepared for a project in Germany or France.

Belgium: Loi sur la Sous-Traitance 1978 and Social Security Joint Liability

Belgium's primary legislation on subcontracting is the Wet betreffende de aanneming van werk (Law of 12 February 1978 on the contract for work), which establishes the legal framework for subcontract relationships in construction. More practically significant for most Belgian contractors is the joint liability for payroll taxes and social security contributions of subcontractors. Under Article 402 of the Belgian Income Tax Code (WIB/CIR) and Article 30bis of the Social Security Act, when a contractor engages a subcontractor, the contractor is jointly liable for the subcontractor's unpaid withholding taxes and social security contributions if the subcontractor has outstanding debts to the Belgian tax or social security authorities at the time of payment. Before paying a subcontractor, the Belgian main contractor must check the subcontractor's debt status via the online lookup tool at financien.belgium.be. If the subcontractor has outstanding debts, the contractor must withhold 15 percent (for withholding tax) or 35 percent (for social security) of the payment and remit it directly to the relevant authority.

Germany: §648a BGB and the Bauhandwerkersicherung

Germany's primary protection for subcontractors and suppliers in construction is §648a BGB (the Bauhandwerkersicherung — construction workers' security). This provision allows any contractor performing construction work (Bauleistungen) to demand that their client provide a security — typically a bank guarantee — covering the claimed value of the work, including anticipated profit. If the client refuses to provide the security within a reasonable period, the contractor can terminate the contract and claim the full agreed remuneration plus costs. The provision is designed to protect subcontractors and main contractors against insolvency of the party above them in the chain, which is the most common cause of payment failure in German construction. Beyond this statutory protection, German main contractors regularly include detailed subcontractor conditions in their subcontracts, requiring the subcontractor to maintain adequate liability insurance, comply with the VOB/B rules, and meet strict documentation requirements for compliance with the Mindestlohngesetz (minimum wage law).

France: Loi du 31 Décembre 1975 and the Direct Payment Right

France has one of the most significant subcontractor protection regimes in Europe, established by the Loi du 31 décembre 1975 relative à la sous-traitance. The most important provision of this law is the droit d'action directe — the direct action right — which allows a subcontractor whose invoices have not been paid by the main contractor to claim payment directly from the ultimate client (the project owner). This is a fundamental departure from the normal contractual structure, which would only allow the subcontractor to sue the main contractor. In France, if the main contractor does not pay the subcontractor within one month of the payment being due, the subcontractor can send a formal mise en demeure (formal notice) to both the main contractor and the project owner. If the main contractor still does not pay, the subcontractor can claim directly from the project owner — who is then obligated to pay and deduct the amount from what it owes the main contractor. This direct payment right requires that the subcontract be officially declared (listed as an approved subcontractor) in the main contract documentation, which must be agreed before work starts.

Netherlands: UAV 2012 §6 and Chain Liability

Dutch construction subcontracting is governed primarily by the UAV 2012 general conditions and by specific legislation on chain liability for payroll taxes (Wet aanpak schijnzelfstandigheid and the accompanying ketenaansprakelijkheid provisions of the Invorderingswet 1990). Under Dutch chain liability rules, a principal contractor who engages a subcontractor can be held jointly liable for the subcontractor's unpaid payroll taxes and social security contributions if the subcontractor defaults. The practical mitigation is the G-rekening system (a blocked account from which the subcontractor's payroll tax obligations are pre-funded), which, when used correctly, shields the main contractor from joint liability. Dutch construction contracts regularly incorporate provisions requiring subcontractors to operate a G-rekening and to remit a specified percentage of each payment to it. For Dutch electricians and plumbers working as subcontractors, understanding and complying with G-rekening requirements is a prerequisite for working with professional main contractors.

Spain: Ley 32/2006 de Subcontratación

Spain has a dedicated construction subcontracting law — Ley 32/2006 reguladora de la subcontratación en el Sector de la Construcción — that establishes maximum chain depth rules. Under this law, a main contractor may subcontract to a first-tier subcontractor, who may subcontract to a second tier, but the second tier may not subcontract further (with limited exceptions). This chain depth limitation was introduced to address the widespread abuse of multi-tier subcontracting chains that were used to obscure responsibility for health and safety violations and payroll fraud. The law also requires all subcontractors on a construction project to be registered in the Registro de Empresas Acreditadas (REA) — a register maintained by regional employment authorities confirming that the company has a stable workforce, adequate professional experience, and a health and safety management system. For a Spanish electrical or plumbing subcontractor, REA registration is a prerequisite for working on Spanish construction projects.

Documentation Requirements for Subcontractor Management

Across all five countries — and most other EU member states — the common thread in subcontractor risk management is documentation. Main contractors must maintain documentation showing: the identity and legal status of each subcontractor (company registration, VAT number, professional certification); confirmation of each subcontractor's compliance status (debt checks in Belgium, REA registration in Spain, G-rekening number in the Netherlands); the subcontract agreement and agreed scope; insurance certificates; health and safety qualifications; and compliance with minimum wage and working time regulations. In Belgium, contractors are required to check and document subcontractor debt status before each payment — not just at the start of the relationship. In Germany, the Mindestlohngesetz requires main contractors to obtain a declaration from subcontractors confirming compliance with the statutory minimum wage for all workers. Building this documentation into the subcontractor onboarding and payment process protects the main contractor against joint liability exposure.

QuotCraft's Subcontractor Module

QuotCraft's subcontractor management module is designed to support the documentation and invoicing requirements of multi-tier subcontracting relationships across European markets. For main contractors managing subcontractors, QuotCraft maintains a subcontractor database with registration details, insurance certificates, and compliance documentation stored against each subcontractor record. Subcontractor invoices can be received and processed within QuotCraft — including Peppol e-invoice reception from subcontractors who are Peppol-connected. For Belgian main contractors, QuotCraft includes the debt check workflow: a reminder is triggered before any subcontractor payment is due, prompting the contractor to verify the subcontractor's current debt status and record the result. For Dutch contractors, G-rekening reference numbers can be recorded per subcontractor and included on payment instructions automatically. The subcontractor cost data flows into project cost reporting, allowing the main contractor to compare subcontractor costs against the budget allocated in the original project quote.