Credits post to bank accounts as deposits, increasing the balances of the funds available for spending, according to Accounting Coach. Debits posted to the same accounts decrease the balances available, whether due to banking fees or withdrawals.
Basic accounting rules require that there be two entries for each transaction made at the bank, Accounting Coach notes. As such, the deposit that posts as a credit to the depositor's account constitutes a debit to the bank's cash account. The debit increases the bank's assets by the deposited amount. The bank lists that same deposit as a credit to its deposits account, which shows that the money is available on demand to the depositor.
When a depositor pays a fee to the bank, the bank takes money from the depositor's checking account and shows the transaction to be a debit to the deposits account at the bank, as stated by Accounting Coach. This debit shows a reduction in the depositor's account equal to the fee amount. The bank records the same amount in its books as a credit to its revenue account since it counts as income for the bank. The bank generally presents such a fee through a memo to the depositor.