This working paper aims to inform the identification of information requirements that can ensure clarity, transparency, and understanding, and by doing so improve trust amongst Parties to the United Nations Framework Convention on Climate Change (UNFCCC) at the negotiating session in Bonn, Germany in March 2014. Parties are negotiating an international agreement for the post-2020 period, to be adopted by 2015. This paper argues that transparency and clarification of post-2020 contributions is one of the main levers to encourage greater ambition and accountability in the 2015 Agreement. To begin it explores the importance of ex-ante information on mitigation contributions; it then provides an overview of contribution types, followed by a list of information requirements by contribution type.