What worker due diligence actually requires: interviews, documentation, and evidence standards

This article is for informational purposes only and does not constitute legal advice. Consult a qualified legal professional for advice specific to your situation.

What this article covers

EU sustainability law, specifically CSDDD and the ESRS standards under CSRD, requires companies to conduct due diligence on workers in their supply chains. The legislation describes what that due diligence must achieve: identification of adverse impacts, prevention and corrective action, meaningful stakeholder engagement, and a complaints mechanism. It is less explicit about what the process looks like on the ground.

This article fills that gap. It covers how worker due diligence is structured in practice, what worker interviews involve and how they are conducted, what documentation standards auditors and regulators expect, and what distinguishes evidence that holds up from evidence that does not. The focus is operational rather than legal. The legal framework is covered in CSDDD explained: what the corporate sustainability due diligence directive means for supply chains.

The audience is companies conducting due diligence on their own supply chains, and non-EU suppliers trying to understand what will be asked of them and why.

Why worker interviews are central to due diligence

Document review and management systems assessment are necessary components of supply chain due diligence, but they are not sufficient. A factory can hold a valid health and safety certification, a signed code of conduct, and a current social audit certificate, and still have workers who are paid below the legal minimum, who cannot refuse overtime without losing their jobs, or who have no safe way to raise a complaint.

The gap between documented policy and operational reality is a well-documented feature of supply chain compliance. EU due diligence law is designed to close that gap. CSDDD requires companies to identify actual and potential adverse impacts based on qualitative and quantitative information from multiple sources, including information obtained through stakeholder engagement. Workers are the primary stakeholders in their own working conditions. Their accounts of those conditions are irreplaceable evidence.

ESRS S2, the standard under CSRD that covers workers in the value chain, requires EU companies to disclose whether they engaged with value chain workers in identifying material impacts on them. Engagement that takes place after the impact assessment is complete, or that is structured so as not to generate any new information, does not satisfy the requirement. The engagement must be meaningful, which in practice means it must reach workers directly and give their accounts real weight in the assessment.

The practical implication is that any worker due diligence process that relies entirely on management interviews, document review, and facility walkthroughs is incomplete. Worker interviews, conducted in a way that generates reliable testimony, are a required element.

Omnibus I narrowed the stages at which stakeholder engagement is required. Under the amended directive, engagement is mandatory at three points: when identifying adverse impacts, when developing action plans and enhanced action plans, and when designing remediation measures. Engagement is no longer required at every stage of the due diligence cycle, but it remains substantive where it applies. A worker interview programme conducted at the identification stage satisfies the engagement obligation for that stage only if it genuinely informs the impact assessment that follows.

How worker interviews are structured

Worker interviews in a supply chain due diligence context are not employment surveys and they are not audits in the traditional sense. They are a form of qualitative evidence collection. The purpose is to understand working conditions from the perspective of people experiencing them, and to identify discrepancies between what management reports and what workers describe.

A well-structured interview programme has several components.

Sample selection. Interviews should be conducted with a sample of workers that reflects the diversity of the workforce: different job grades, genders, employment types including direct and contract workers, and where relevant different nationalities or migrant statuses. A sample drawn entirely from senior production workers or from workers selected by management will not capture the conditions faced by the most vulnerable members of the workforce. The sample size depends on the size and complexity of the facility, but a minimum of 10 to 15 percent of the workforce is a common benchmark for a meaningful primary assessment.

Interview setting. Interviews must be conducted in a setting where workers can speak freely. This means off-site where possible, or in a private location within the facility that is not observed by management. Interviews conducted on the production floor, in the presence of supervisors, or in a setting where workers can be identified by management afterward do not generate reliable testimony. Workers who fear retaliation will not report violations, and the absence of reported violations in a compromised interview setting tells you nothing about actual conditions.

Language and interpretation. Interviews must be conducted in the worker’s own language. Using management-provided interpreters creates a conflict of interest that compromises the reliability of the evidence. Where specialist interpreters are required, they should be sourced independently of the facility.

Question design. Interview questions are open-ended and designed to elicit accounts of actual experience rather than yes-or-no responses. A question such as “do you receive your wages on time?” generates a binary response that a worker may answer affirmatively out of caution even if the reality is more complex. A question such as “can you walk me through how you found out what your pay would be when you started here, and how it works now?” generates an account that can be cross-referenced against payroll records, other worker interviews, and the regulatory minimum wage for the location.

Topics covered. A worker interview programme for CSDDD or ESRS S2 purposes typically covers: wages and the process by which workers understand and verify what they are paid; working hours including overtime practices and whether overtime is voluntary; freedom to leave employment and whether any restrictions or debt arrangements exist; health and safety conditions in the work area; access to a complaints or grievance mechanism and whether workers have used it or know how to; and whether workers have experienced or witnessed any form of harassment, discrimination, or coercion.

Documentation of findings. Interview findings must be recorded in a way that preserves the substance of what was said without identifying individual workers. The record should note discrepancies between worker accounts and management representations, between different workers’ accounts of the same practices, and between worker accounts and what documentary evidence suggests. These discrepancies are often the most significant findings.

What documentation is required

Documentary evidence in worker due diligence serves two functions. It substantiates or contradicts worker testimony. And it constitutes the auditable record that a company subject to CSDDD or CSRD must be able to produce to demonstrate that it conducted due diligence.

The documentation requirements vary by subject area.

Wage compliance. Payroll records showing gross and net pay by worker grade for the assessment period. Records of all deductions, including accommodation, food, and any loan repayments, and the contractual basis for each deduction. Records of the minimum wage or living wage benchmark applicable at the location and the date from which each rate applied. Where workers are paid by piece rate rather than time rate, records of the production targets and rates used to calculate earnings.

Working hours. Attendance and timekeeping records for the assessment period. Records of overtime worked, the rate at which it was compensated, and any written consent obtained. Where the facility operates shift patterns, records showing shift schedules and actual hours worked by shift.

Employment terms. Signed employment contracts or offer letters for a sample of current workers, covering job title, pay rate, working hours, and termination conditions. Where contract workers are used, the agreements between the facility and any labour recruitment agencies, including the fees charged and whether workers bear any part of those fees.

Health and safety. Incident records for the assessment period, including near-misses, lost-time injuries, and fatalities. Training records showing what safety training workers received and when. Chemical management records where relevant. Records of any regulatory inspections and their findings.

Complaints mechanism. Records showing that a complaints mechanism exists, how it is communicated to workers, and whether any complaints have been received and how they were handled. The absence of complaints is not itself evidence that the mechanism is functioning: it may indicate that workers do not know about it, do not trust it, or fear retaliation for using it. Worker interview findings on this point are often more informative than the complaints register.

Recruitment and migration. Where the facility employs migrant workers, records of the recruitment process including any fees paid at origin and whether those fees were later reimbursed by the employer. The presence of recruitment fees paid by workers that have not been reimbursed is a significant risk indicator for forced labour.

What counts as sufficient evidence

The question of sufficiency is one of the most practically important and least clearly answered aspects of EU due diligence law. Neither CSDDD nor the ESRS standards define what sufficient evidence looks like. They describe what the due diligence process must achieve and leave the evidentiary standard to professional judgment.

In practice, sufficiency is assessed by reference to several factors.

Corroboration across sources. Evidence that is consistent across worker interviews, document review, and facility observation is stronger than evidence from a single source. A worker account of wage deductions that is corroborated by payroll records and by the accounts of other workers interviewed independently provides a more reliable evidential basis than an account that conflicts with documents or that no other worker corroborates. Where sources conflict, the conflict itself is a finding that requires further investigation.

Specificity and detail. Detailed, specific accounts from workers, including names of supervisors, specific amounts, dates, and sequences of events, are more credible than general statements. Vague confirmations of general compliance are the form of testimony most likely to be shaped by the interview setting rather than reflecting actual experience.

Independence of collection. Evidence collected through independent channels, meaning through interviewers who have no relationship with facility management and through document review that was not mediated by facility staff selecting which documents to provide, carries more weight than evidence filtered through the facility’s own representatives.

Contemporaneity. Current records and recent accounts are more reliable than records that have been reconstructed or accounts of conditions that prevailed some years ago. Due diligence is an assessment of current and potential future impacts, not a historical audit.

Consistency with sector and location risk. Evidence must be interpreted against known risk patterns in the relevant sector and geography. A facility in a sector with documented patterns of excessive overtime, in a location where labour law enforcement is weak, that produces no evidence of any overtime irregularity, warrants more scepticism than the same absence of findings in a lower-risk context. Risk-based interpretation of evidence is not the same as assuming guilt; it is a professional standard for weighing what you find against what you might reasonably expect.

The concept of sufficient evidence in CSDDD is closely related to the concept that runs through the regulation’s enforcement provisions: a company that conducted a genuine, well-structured, and documented due diligence process and identified no adverse impacts is in a materially different position from a company that conducted a superficial assessment and reached the same conclusion. The process must be defensible, not just the finding.

How fieldwork is typically organised

A worker due diligence fieldwork programme for a mid-sized supply chain facility typically runs over two to three days on site, preceded by document request and review and followed by findings analysis and reporting.

The pre-visit phase involves sending a document request to the facility covering the categories described above, reviewing those documents before arrival to identify gaps and discrepancies that will focus the on-site work, and background research on the facility, sector, and location including any civil society reporting, media coverage, or prior audit findings.

The on-site phase involves a management opening meeting to explain the scope and process, facility walkthrough with attention to health and safety conditions, working environment, and any visible indicators of workforce composition, followed by document review of records held on site, and then worker interviews conducted off the production floor or off-site.

The worker interview component typically takes one to two days depending on sample size. Interviewers work in pairs where possible: one conducting the interview, one taking notes. Findings are not discussed with management during the on-site phase.

The closing management meeting covers process findings, meaning observations about the facility’s systems and records, but does not disclose individual worker accounts or specific interview findings in a way that could allow management to identify which workers said what.

The post-visit phase involves cross-referencing interview findings against documentary evidence, drafting the findings report, and preparing the corrective action recommendations where issues are identified.

What suppliers need to be prepared for

For non-EU suppliers whose EU buyers are subject to CSDDD, the worker interview and documentation process described above is what will arrive at their facility. Understanding what it involves removes the element of surprise and allows preparation that makes the process more effective for both sides.

The most common preparation failures are not about having something to hide. They are about not having organised what exists. Payroll records that exist in a payroll system but cannot be extracted in a usable format. Incident records that were kept but not in a consistent way across periods. Employment contracts that were signed but not retained in a central location accessible to the person managing the assessment visit.

Facilities that have conducted SMETA 4-pillar audits or equivalent have typically already gone through a version of this process and hold the documentation in a reasonably accessible state. Facilities that have not been audited recently face a more significant preparation task.

The practical starting point is a self-assessment against the documentation categories listed above, identifying what exists, where it is held, and what gaps need to be filled before an external assessment. For worker interview purposes, the most useful preparation is ensuring that workers know that an assessment is happening, that the interviews are confidential, and that participation is voluntary. Facilities that brief workers through management channels in a way that could be interpreted as instructing them on what to say undermine the reliability of the interview process and are likely to generate findings that create more problems than they resolve.

For guidance on how EU buyers are currently structuring their supplier assessment processes in response to CSDDD, see How EU buyers are changing their supplier requirements because of CSRD and CSDDD.

Verdandi monitors CSDDD, CSRD, and ESRS continuously, so companies building worker due diligence programmes are working from current requirements as member state transposition deadlines approach and enforcement practice develops. Start for free.