There are a number of sources for the information in this database:
The information on environmentally related taxes was in the first hand collected from ministries of finance in OECD member countries. Information on environmentally related fees and charges was in many cases later supplied by persons working in the respective ministries of environment or similar.
In 1998, a survey of tradable permits systems, deposit refund systems and environmentally motivated subsidies in OECD member countries was undertaken.
This information was entered into the database structure and sent to delegates to the former Working Party on National Environmental Policy (WPNEP) under OECD's Environment Policy Committee for verification, update and completion.
The delegates were also asked to provide information on voluntary policy approaches, which were not included in the 1998 survey.
More information, and many rounds of updates of the information, have been provided by a set of contacts in the respective countries, many of whom are delegates to OECD's Working Party on Integrating Environment and Economic Policies.
For most of the countries that are members of, or related to the EEA, but not being members of the OECD, the initial data source was the "Sourcebooks on Economic Instruments", information prepared by the Regional Environment Centre in Szentendre, Hungary, which also entered the relevant information into the database structure. This information was sent to the National Focal Points of the EEA in the respective countries for verification, update and completion.
At present, a password-protected web-site is used where autorised contacts in the respective countries can enter new or additional information on line. By clicking here, you can see a table with details on the latest updates for each country. No updates have been made since 2007 to the information regarding the EEA-related countries that are not members of OECD, except some recalculations of tax rates and similar expressed in euro, using exchange rates for later years.