Greater fiscal transparency is seen by its advocates as a means of improving economic governance arrangements in ways which, by promoting fiscal stability, will in turn improve the functioning of the government sector and facilitate improvements in the economic environment for the private sector. 'Fiscal transparency' is much acclaimed by policy-makers, not only in the UK Treasury but also by the IMF and OECD. Fiscal transparency can have substance or can just be voguish incantation. This article explores the meaning of fiscal transparency, by examining its structure and evaluating criteria for assessing the degree of fiscal transparency attached to particular sets of circumstances. It explores the link between transparency and accountability, developing the distinction between event and process transparency. Consideration is given to the trade-off between the value of sunlight (to employ an analogy) and the danger of over-exposure. The performance of the United Kingdom against emerging international best practice is examined, with regard to both public expenditure and taxation. By international standards, UK fiscal transparency is high. Nevertheless, there is a major gap between UK rhetoric and practice, indicating a divergence between nominal and effective transparency. This is evidenced by: frequent changes in public expenditure definitions; the non-publication of important analyses; the location of certain liabilities 'off-balance sheet'; and a lack of candour about tax policy.