OECD (1999) gives the following definition of taxes:
"compulsory, unrequited payments to general government. Taxes are unrequited in the sense that benefits provided by government to taxpayers are not normally in proportion to their payments."
This definition is consistent with the definition of taxes in the European System of Accounts (ESA 95 – European Commission 1996).
The terms charges and fees are often used interchangeably. As opposed to taxes, they are seen as payments for a service, i.e. requited payments. The OECD defines charges and fees as: "compulsory, requited payments to either general government or to bodies outside general government, such as for instance an environmental fund or a water management board."
The term levy is sometimes used to cover all kinds of compulsory payments. Taxes on products are sometimes called duties or excise duties.
The legal definition of taxes may differ between countries, and may also be different from the definition used in the national accounts. Both definitions are relevant for environmental tax statistics. The legal definition of taxes has an influence on how policy makers can use them as instruments for environmental protection. The national accounts definition improves international comparability of the statistics, and allows integration of the tax data with the national accounts and with systems of integrated environmental and economic accounting. The environmental tax statistics framework uses the tax definition of the national accounts, but countries may choose to describe environmental taxes from both the legal and the national accounts perspective.
Eurostat, "Environmental taxes - A statistical guide", Office for Official Publications of the European Communities, 2001