Automatic stabilizer

In macroeconomics, automatic stabilizers are features of the structure of modern government budgets, particularly income taxes and welfare spending, that act to reduce fluctuations in real GDP.

The size of the government budget deficit tends to increase when a country enters a recession, which tends to keep national income higher by maintaining aggregate demand. There may also be a multiplier effect. This effect happens automatically depending on GDP and household income, without any explicit policy action by the government, and acts to reduce the severity of recessions. Similarly, the budget deficit tends to decrease during booms, which pulls back on aggregate demand. Therefore, automatic stabilizers tend to reduce the size of the fluctuations in a country's GDP.

In the United States, state governments are barred by their constitutions from running budget deficits so in those cases money saved in rainy day funds can be used as a stabilizer to avoid cutting services or raising taxes, both of which are contractionary to the economy.