Fiscal capacity is the ability of the state to extract revenues to provide public goods and carry out other functions of the state, given an administrative, fiscal accounting structure. In economics and political science, fiscal capacity may be referred to as tax capacity, extractive capacity or the power to tax, as taxes are a main source of public revenues. Nonetheless, though tax revenue is essential to fiscal capacity, taxes may not be the government's only source of revenue. Other sources of revenue include foreign aid and natural resources.