Petty Cash Funds are maintained by a designated Custodian, who must be an ongoing, permanent UVM employee. Generally speaking, the fund should need replenishment at least once a month; that is, the total of the expenditures over a four-week period should equal the amount of the fund. This will vary, of course, but the objective is to minimize the chance of significant theft. If the fund does not need replenishing at least once a month, then it is too large.
The Petty Cash User Guide (PDF) describes the various types of petty cash funds; how to open, replenish, reduce, and close a fund; the necessary forms for each step of the process; and how petty cash accounting entries are created.