High Quality Content by WIKIPEDIA articles! Rainy day fund, rainy day reserve, or emergency fund are terms used to describe a reserved amount of money to be used in times when regular income is disrupted or decreased in order for typical operations to continue. In the United States, the term is usually used to apply to the funds maintained by most U.S. States to help deal with budget shortfalls in years where revenues do not match expenditures. This is critical to the operations of most state governments which do not permit the government to take on debt, meaning that services would have to be cut in the absence of reserve funds.New York state Comptroller Thomas DiNapoli recommended in March 2010 that the state require that one half of surplusses be deposited into the rainy day fund.