The current balance in a bank account is the amount in the account at the start of a business day. The available balance is what the account holder can actually withdraw at a given point in time, according to Mutual Savings Credit Union.
First Tennessee indicates that some direct wire transfers and online bill payments automatically reduce an account holder's current balance. Other transactions, such as debit payments, processing checks and automatic drafts do not immediately affect the current balance. They do reduce the available balance so that the account holder is not able to go over the account limit when making a withdrawal or payment.