What is the book for?
The subcontracting log allows for the identification and tracking of successive contracts within a project and under a contractor’s commission. It is mandated by Law 32/2006 and further developed by Royal Decree 1109/2007. The information it contains helps to determine who is performing the work, for whom, and at what stage of the supply chain.
This is not a voluntary supplier registry or a site access list. Anyone entering the construction site may belong to a company whose involvement must be documented beforehand. The purpose of this logbook is to connect the administrative data with the actual activity that will be carried out.
Who should have it
The contractor required to maintain the logbook must obtain it from the labor authority corresponding to the work site, in accordance with the applicable procedure. This obligation is not automatically transferred to the health and safety coordinator, nor is it fulfilled simply because another company involved in the project has its own logbook.
In a project with multiple contractors, there may be separate logbooks for each contractor’s work. It is essential to clearly identify which work stream each contractor is responsible for documenting. While the subcontractor provides the necessary information and fulfills its obligations, this does not eliminate the contractor’s legally mandated responsibility for maintaining the logbook.
What should be noted
Subcontracting arrangements are listed chronologically and prior to the commencement of the corresponding work. The regulations stipulate information regarding the company or self-employed individual, the client, the level of subcontracting, the subject matter of the contract, and the individuals responsible for organization and management, in addition to other preventive information included in the form.
Documentation is also required on aspects such as the submission of the relevant section of the health and safety plan, coordination instructions, and approvals for any exceptional extensions. The person responsible for health and safety coordination during execution and any changes in that appointment must be identified. The data is completed according to the regulatory template, not through informal selection.
Relationship with subcontracting limits
The book helps verify the position of each party involved and compliance with the subcontracting regulations. The regulations establish limitations and specific scenarios that must be analyzed before authorizing a new link in the chain. Registering a company does not legalize a subcontract that violates applicable requirements.
Exceptional extensions require the legally established conditions and procedures. They should not be used as a routine mechanism to address insufficient planning. When specific approval and notification are required, the justification must be maintained and carried out within the established timeframe. Traceability ensures that the actual and documented supply chains do not evolve separately.
Access, communications and preservation
The book must remain on site throughout the execution of the project, as stipulated. The regulations recognize access for the parties entitled to it and require notification of each subcontract to the health and safety coordinator and, where applicable, to the representatives of the affected workers.
The contractor must keep it for five years after the completion of their participation in the project. In building projects subject to the regulations, a completed copy is given to the project manager for inclusion in the building logbook, with the contractor retaining the original. The final agreement must include provisions for these obligations.
Differences compared to other instruments
The REA ( Registry of Accredited Companies) certifies certain company requirements; the logbook documents the construction process. The health and safety plan outlines the contractor’s preventive measures. The incident logbook serves to monitor and track the plan, with its own rules for recording and reporting.
A platform can help link this information, but an internal record should not be confused with the required regulatory instrument. The method of enabling and using it must comply with the procedure of the competent authority. Digitizing a copy does not, in itself, modify the obligations or the responsible parties.
Practical example
A contractor brings in a company for one phase of the installations. Before starting, they check the planned subcontracting, obtain the necessary information, make the corresponding notes and communications, and organize the coordination. The company then proposes bringing in another entity for a portion of the work.
The proposal is analyzed before the entity begins: its position and applicable limits are reviewed, requirements are checked, and the ledger is updated as needed. There’s no waiting until the end of the month to reconstruct what happened. This way, the document helps control actual decisions and doesn’t simply describe a chain of events that has already been executed.
Common mistakes
The most common mistakes are making entries after the start date, mistaking the logbook for a personnel list, and assuming that the existence of a coordinator replaces the contractor’s responsibilities. Another mistake is forgetting to record changes in companies, representatives, or coordination that should be documented.
Effective management assigns a person responsible for keeping information up-to-date and establishes procedures for receiving proposals for new subcontracts. The review process should compare the written information with the actual work being done. The preventive and traceability value of the logbook depends on this correspondence and on adherence to its communications and deadlines.
