A bank statement is an official summary of financial transactions occurring within a given period for each bank account held by a person or business with a financial institution. Such statements are prepared by the financial institution, are numbered and indicate the period covered by the statement, and may contain other relevant information for the account type, such as how much is payable by a certain date. The start date of the statement period is usually the day after the end of the previous statement period.

Once produced and delivered to the customer, details on the statement are not normally alterable; any error found would normally be corrected on a future statement, usually with some correspondence explaining the reason for the adjustment.

Bank statements are commonly used by the customer to monitor cash flow, check for possible fraudulent transactions, and perform bank reconciliations. Historically they have been printed on one or more pieces of paper, and either mailed directly to the account holder or kept at the financial institution's local branch for pick-up. In recent years there has been a shift towards paperless electronic statements, and many financial institutions now also offer direct downloads of financial information into the account holders' accounting software to streamline the reconciliation process. Bank statements are important documents and are usually required to be retained for audit and tax purposes for a period set by relevant tax authorities.

To enable account holders to track account activity on an ongoing basis, many financial institutions offer a non-official transaction history before the official bank statement is produced. Such activity may be viewed on or printed from the financial institution's website, a smartphone application, available via telephone banking, or printed by some ATMs.

Transaction histories or account balances may also be shared with other financial institutions, when the account holder gives permission, through open banking to provide services such as account aggregation. An aggregation service only lets the software view an account balance, not actual transactions.

Historically, bank statements were paper statements produced periodically on a monthly, quarterly or annual basis. Since the introduction of computers in banks in the 1960s, bank statements have generally been produced monthly. Bank statements for accounts with small transaction volumes, such as investments or savings accounts, may be produced less frequently. Depending on the financial institution, bank statements may also include certain features such as the canceled cheques (or their images) that cleared through the account during the statement period. Paper statements are typically posted to a customer's home address, and sometimes a copy may be posted to, say, an accountant or guardian.

Some financial institutions use the occasion of posting bank statements to include notices such as changes in fees or interest rates or to include promotional material.

Financial institutions are required to produce paper statements to customers unless the customer requests either electronic statements or no statements at all. Historically, the production of statements was regarded as part of the banking function, the cost of which was part of providing the service. More recently, however, to encourage customers to opt to receive electronic statements, some financial institutions charge a fee for paper statements.