As part of introducing accrual accounting in the public sector, many governments have – voluntarily – implemented the International Public Sector Accounting Standards (IPSAS) for financial reporting. Amongst other claimed benefits, IPSAS have been argued to facilitate comparison of adopters’ financial reports and to lead tofavourable conditions on credit markets. However, governments that are confronted with the implementation decision face a trade-off between unaltered adoption, partial adoption, adaptation and non-adoption of standards. Drawing on insights from the literature on standardization and practice variation, this paper analyses the reasons, expressed by various actors from nine European countries, for deviating from implementing unaltered IPSAS and proposes a taxonomy of these reasons. The results show that, first, substantial deviations exist, and second, there is a plethora of reasons for them. These deviations are presented and then structured in the further course of the paper. As a consequence of deviations, achieving comparability as the central aim of standardization runs the risk of being undermined.