The situation in which an economy operates with insufficient expenditure level is called as having a deflationary gap. In order to reach the full employment output level, in other words, to close the deflationary gap by eliminating spending gap in the economy, it is required to shift aggregate expenditure function upward. For the government to shift aggregate expenditure function upward there are three ways: decrease taxes, increase public expenditures and make the investments to be more profitable. Arranging fiscal policy to increase aggregate expenditures is called as expansionary fiscal policy.