Petty Cash is a set amount of cash you have on hand for small items. When the amount in the Petty Cash fund gets low, you write a check to bring it back to the amount of the Petty Cash fund. As an example, let's say you have a $350 Petty Cash fund. You will always have the $350 on the books as the amount of Petty Cash. No entries are made to this account unless you increase or decrease the amount of this fund. When you replenish petty cash (Say you are now down to $20. Since you see that your petty cash is low, in this case by $330, you write a check for $330 to get that amount from the bank in cash to bring your petty cash back to $350), you will debit the expense accounts involved and credit cash. You will have kept receipts for the $330, which will tell you the respective accounts to debit.