The issue of trust between Multinational Enterprises (MNEs) and tax administrations is a vital part of the tax system, but relatively little studied. Building on previous OECD research on tax morale, which measures taxpayer perceptions and attitudes towards paying and evading taxes, this report presents new data on how tax administrations perceive MNE behaviour towards tax compliance. With a particular focus on the challenges facing developing countries, this report brings together this data with previous data on MNE perceptions, and the outcomes of a series of regional roundtables on tax morale held between tax administrations and MNEs. Having identified a number of challenges around trust, transparency and openness, the report sets out a range of approaches to help build trust, improve communications, and build more effective relationships between taxpayers and tax administrations.