Cash is an easier target to defraud than funds that have been deposited into a bank account.
Methods to Mitigate the Risk
Many organisations accept cash donations, membership fees or other income. Cash can easily be taken, is difficult to trace and is therefore a significant risk to fraud. To reduce the risk of cash theft, encourage deposits directly into the organisations bank account as first preference, or otherwise donate or pay by credit card (of course credit card fees will need to be considered).
Of course, controls must then be maintained over the relevant bank accounts to ensure cheque fraud or online payment fraud does not occur.