Back Ověřovací číslo transakce Czech Transaktionsnummer German Número de autenticación de transacción Spanish Գործարքների նույնականացման համարներ Armenian TAN-code Dutch Karta kodów jednorazowych Polish Transaction authentication number Slovak
A transaction authentication number (TAN) is used by some online banking services as a form of single use one-time passwords (OTPs) to authorize financial transactions. TANs are a second layer of security above and beyond the traditional single-password authentication.
TANs provide additional security because they act as a form of two-factor authentication (2FA). If the physical document or token containing the TANs is stolen, it will be useless without the password. Conversely, if the login data are obtained, no transactions can be performed without a valid TAN.