The Global Tax Expenditure Database collects national reports on tax breaks in 101 countries from 1990 to the present. Based on these data, the development of tax breaks in 38 OECD countries from 1999 to date is examined.

Data check that reporting is often incomplete, even in countries with high GDP and comprehensive tax coverage. For a subset of the 16 OECD countries where (relatively) continuous reporting takes place during this period, consideration is being given to developing tax breaks for private households and companies. This shows that data availability improves over time. A weak positive trend in terms of lost tax revenue can be identified by the development of tax breaks for companies, mainly led by the Netherlands and Ireland. Both countries want to strengthen their business location through generous tax breaks for companies. Tax breaks for private households, above the level of concessions for the average company in the countries under consideration, do not show a significant trend over time, however, for example, tax breaks to avoid private households and companies were overused during the financial crisis. 2008/09. Regular reporting is required at the national level to compare tax breaks between countries and scrutinize their effectiveness, with transparent definitions and unified standards. Regular inspections by a commission with relevant experts will result in consistency and comparability.