When you write a check, authorize an electronic debit or deposit money into a checking account, the transaction must be processed. The term "pending" refers to any transaction the bank is aware of but hasn't yet processed or posted. Pending transactions of different types affect the amount of money you have available in different ways.
Pending Transactions and Funds Available
Cash deposits are available immediately or at least the same business day. Non-cash deposits show as pending but are typically available the same or next business day unless there is a hold on the money. Banks hold transactions as pending when they are waiting for funds to clear, which can take a few days.
Banks immediately list any debit or withdrawal transaction as pending and reduce your available funds. In some cases, the debit amount may exceed the pending transaction. Suppose you use your debit card at a restaurant. The waiter "swipes" your card. The bank's computer system confirms you have the money to cover the bill and lists the amount as a pending transaction. If you add the tip, it increases the bill and that's the figure that will actually be debited when the restaurant sends the completed transaction to the bank.