Overdraft protection is not a required feature of most checking accounts, nor is there typically a situation where a customer cannot opt out. It is an optional service offered by banks that allows customers to cover transactions that exceed their available funds, often by linking to another account or line of credit. Customers usually have the choice to opt in or opt out when opening their account or at any time afterward. Without opting in, transactions that would overdraw an account are typically declined. Major banks provide overdraft protection as an optional safety net to avoid declined transactions and fees, but customers are generally free to decline this service if they prefer.