OECD-based Due Diligence

The sourcing of tin mineral (cassiterite), certain tin metal and chemicals are subject to regulations in several jurisdictions including under Section 1502 of the US Dodd Frank Act, Regulation (EU) 2017/821 on responsible minerals and the LME Responsible Sourcing Rules. The tin sector has led the implementation of the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas and its Supplement on ‘3T’ minerals upon which mandatory rules are based and recognises the need for due diligence audits to smelters. Tin Code Standard 7.3 has a mandatory expectation for evidence of third-party verification of the company activities.

Responsible sourcing

Companies 1,2 will evaluate potential risks, seek to avoid support to conflict, human rights and other significant abuses and publicly report on their efforts according to international expectations and laws, in particular the OECD Due Diligence Guidance 3T Supplement.3

  1. Companies with smelters will seek to be third-party assessed against recommended criteria
  2. Companies without smelters will seek to apply aspects of the recommended criteria relevant to their own circumstances.
  3. The criteria recommended for standard 7.3 is the ITA-RMI Assessment Criteria for Tin Smelting Companies v2 (Mar 2021) criteria 7.3. Other criteria may be utilised if deemed equivalent after equivalence checks against criteria 7.3 and 7.3 guidance by ITA experts.

In the Tin Code, ‘responsible sourcing’ refers to supply chain due diligence and does not encompass all other ESG standards which are separately evaluated.

The assessment criteria recommended by the Tin Code for standard 7.3 is the ITA-RMI Assessment Criteria for Tin Smelting Companies (version 2, 25th March 2021) which was developed including through public consultation.

In order to maintain close alignment with the OECD Due Diligence Guidance, ITA completed an independent OECD Alignment Assessment of the standards of the Tin Criteria which were confirmed as “Fully Aligned”.

ITA-RMI Assessment Criteria for Tin Smelting Companies

The International Tin Association (ITA) and the Responsible Minerals Initiative (RMI) have developed a new core audit requirement document, now known as the “Assessment Criteria for Tin Smelting Companies”. The Criteria are designed to align with the 3T Supplement of the internationally recognised OECD due diligence guidance, assist with the new London Metal Exchange (LME) responsible sourcing requirements, and satisfy other upcoming requirements such as the EU Minerals Due Diligence Regulation. The document brings together multiple views of complex due diligence expectations into one new harmonised text. Tin smelters can be assessed against the Criteria by assessment processes of Tin Code Assurance (ISAE 3000) or the RMI (ISO 19001). This work aims to improve due diligence across the tin supply chain and encourages transparency to help to streamline information requests through the supply chain.

The Criteria incorporates consultation feedback from a broad spectrum of stakeholders across the tin supply and has been improved by:

  • Focusing exclusively on the tin value chain
  • Structuring to reference each Step of the OECD Due Diligence Guidance Supplement on Tin
  • Highlighting additional, separate regulatory or downstream expectations
  • Outlining practical expectations for red-flag review of suppliers
  • Explaining how smelters may use OECD-aligned joint industry initiatives for due diligence support
  • Clarifying terminology and separating procedural or guidance text for auditors


In March 2021, version 2 (25th March 2021) of the Criteria was published with minor clarifications to reflect the “Fully Aligned” score for ‘policies and standards’ aspect of the independent OECD Alignment Assessment.

ITA and RMI have also developed internal guidance to the Criteria which is aimed at ensuring common understanding of auditors and auditees as well as assessment process managers and each organisation will develop tools which reflect that guidance.

Download the ITA-RMI Assessment Criteria in English
Download the ITA-RMI Assessment Criteria in Chinese
Download the ITA-RMI Assessment Criteria in Indonesian Bahasa
Download the ITA-RMI Assessment Criteria in Spanish
Download the ITA-RMI Assessment Criteria in Portuguese

Download the independent OECD alignment assessment report

Joint Statement regarding the EITI

International Tin Association (ITA) and its members believe that appropriate natural resource management can support social and economic growth and avoid potential negative impacts in the communities in which we operate.

We recognise that transparency can promote wider understanding of natural resource management and good practices. Increasing openness and trust between companies and governments regarding payments related to natural resource extraction can help to reduce corruption, improve public understanding, and support sustainable development. With this statement we jointly express our support to the 12 founding principles that are the cornerstone of the Extractives Industries Transparency Initiative (EITI).

EITI is referenced in the expectations of Tin Code standard 1.5 (Transparency), standard 7.3 (Responsible Sourcing), and standard 8.8 (Influencing Suppliers of Large-Scale Minerals).

Download the Joint Tin Industry EITI Statement

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