Specifically, realised capital gains, employees’ mandatory and voluntary pension contributions are treated in the same way in the IDD as they are in the national assessment made by the Danish government.12 As a result, these differences are theoretical and do not de facto impact the comparison between OECD and official Danish data. It remains unclear whether the Gini coefficient under full compliance with the OECD standards would be lower or higher since the inclusion of realised capital gains tends to increase inequality whereas inclusion of voluntary pension contributions (among current transfers paid) tends to decrease inequality (see above). A tax reform in 2009 restricted the tax deductibility of some pension contributions, which resulted in lower contributions.