Modern slavery due diligence: what to ask suppliers for

Most modern slavery statements describe policies. Fewer describe evidence. The difference matters, because a statement is only as credible as the checks behind it, and those checks happen in the supplier file.

This guide sets out what the law requires, what the guidance expects, and what to ask suppliers for so that your due diligence can be shown rather than only described. It is general information, not legal advice.

What section 54 requires

Section 54 of the Modern Slavery Act 2015, the transparency in supply chains provision, applies to a commercial organisation that:

• is a body corporate or a partnership, wherever it was formed;
• carries on a business, or part of a business, in the UK;
• supplies goods or services; and
• has a total turnover of £36 million or more, including the turnover of its subsidiaries.

Such an organisation must publish a slavery and human trafficking statement for each financial year. The statement must describe the steps it has taken during the year to ensure that slavery and human trafficking are not taking place in its supply chains or in its own business, or say that it has taken no such steps.

For a company, the statement must be approved by the board and signed by a director. It must be published on the organisation’s website, with a link in a prominent place on the homepage. Government guidance asks organisations to publish within six months of their financial year end and to keep earlier statements available.

The Act lists six areas a statement may cover: the organisation’s structure, business and supply chains; its policies; its due diligence processes; where the risks lie and how they are assessed and managed; its effectiveness, measured against performance indicators it chooses; and training. The areas are recommended rather than mandatory, but they are the structure most readers, and the government’s guidance, use.

The duty is enforced by the Secretary of State, through civil proceedings in the High Court for an injunction. Adding a statement to the government’s modern slavery statement registry is not yet mandatory, but it is strongly encouraged, and the registry says it will become mandatory in future. The government has announced other changes to the reporting requirements; until they take effect, organisations report under the current rules.

What the 2025 guidance expects

The Home Office published updated statutory guidance on section 54 in March 2025. Its emphasis is on what organisations actually do: specific steps to prevent, detect and remediate modern slavery; risk assessments that identify the most significant risks; engagement with suppliers and with workers; indicators that measure progress; and openness about what has been learned. It distinguishes foundational disclosures from more advanced ones, and encourages organisations to move towards the second kind.

The practical consequence is that a statement saying “we have a supplier code of conduct” is weaker than one saying how many high-risk suppliers were assessed, what was found and what changed as a result. The second kind of statement needs supplier evidence behind it.

What to ask suppliers for

Ask for evidence in proportion to the risk. A supplier of office services in the UK and a supplier of labour-intensive goods from a high-risk region do not need the same file.

Use the ILO indicators to focus the review

The International Labour Organization publishes eleven indicators of forced labour: abuse of vulnerability, deception, restriction of movement, isolation, physical and sexual violence, intimidation and threats, retention of identity documents, withholding of wages, debt bondage, abusive working and living conditions, and excessive overtime.

They are a practical way to decide what evidence to ask for, because each one points at something that can be checked:

• Retention of identity documents. A policy that workers keep their own passports and identity papers, and audit evidence that it is followed.
• Withholding of wages and debt bondage. Payroll practices, payslips sampled during audits, and a policy that workers pay no recruitment fees.
• Excessive overtime. Working-hours records, and how hours above the legal limit are handled.
• Restriction of movement and isolation. Accommodation arrangements, where the employer provides housing.

Red flags

• Workers, including agency workers, paying recruitment fees.
• Heavy use of labour agencies with no visibility of how they recruit.
• Audit reports with no findings at all, especially from audits announced in advance.
• Corrective actions that stay open for months without explanation.
• A group policy that does not name or cover the supplier’s own entity.
• Questionnaire answers that match other suppliers’ answers word for word.

Recording what you found

Due diligence is easier to report, and to defend, when each supplier review leaves a record: the evidence requested, what was received, what it showed, what was missing, the decision taken and any follow-up. That record is also the raw material for the indicators the 2025 guidance asks for, such as the share of high-risk suppliers assessed and the number of corrective actions closed.

The checks themselves are the same ones that apply to any supplier evidence. How to review supplier compliance evidence covers them, and checking questionnaire answers against evidence covers the questionnaire most programmes start with.

Where DataStruct fits

DataStruct runs your due diligence requirements against the documents a supplier returns: policies, audit reports, corrective action records and questionnaire answers. Each finding links to the page or section it came from, related material is kept apart from support, and where nothing supports a requirement the finding says so, which gives you a specific gap to send back to the supplier.

It does not assess modern slavery risk itself, contact suppliers or decide whether a supplier is acceptable. A reviewer decides, and the decision is recorded. The same programme structure is described for supplier compliance review.