As state lawmakers head into the budget-writing season, some will face the unpleasant task of figuring out how to fill projected shortfalls. In most cases, that conversation will include a debate on whether to withdraw cash from the state’s rainy day fund.

Some states count on their rainy day savings during recessions to limit budget cuts, while others strive to put away enough savings to avoid cuts altogether. But many states lack clear guidance about when to take money out of rainy day accounts, for what purposes and how much.

Rainy day funds have been around for decades. Among the 46 states that have them, only half have laws that clearly express what they're seeking to achieve with them, according to a recent Pew Charitable Trusts report. Two states -- Wyoming and Kentucky -- lack any statutory or constitutional direction about their purpose or proper use.

That means legislators have to argue each time finances become a problem.