Progressive taxes and the benefit system reduce the impact of changes in demand on disposable income, consumption, and the equlibrium level of national income. Disposable income - take-home pay- is the main determinant of how much people desire to spend. Hence, if disposable income is not allowed to fall as much as it would otherwise during a recession, the downturn will be moderated. On the other hand, if disposable income is not allowed to rise as rapidly as it would otherwise during a boom, the boom will not get out of hand, causing prices to rise, among other things. The government automatically swings into deficit when there is a recession, and back towards surplus when the economy booms.