NDC Transparency Check provides a robust reference to assess whether the mitigation efforts communicated by countries through Nationally Determined Contribution (NDCs) are clear, transparent and understandable, in terms of the requirements set out in the Paris Agreement, its accompanying decision (1/CP.21) and Annex I to decision 4/CMA.1, which sets out the "information to facilitate clarity, transparency and understanding of nationally determined contributions" to accompany NDCs. Legally, the Annex is only binding from the second NDC onwards. However, Parties are "strongly encouraged" to apply the Annex to updated NDCs.

The methodology was developed by Andrew Marquard and Harald Winkler (University of Cape Town) and benefited by the review of Climate Transparency partners.