PCI DSS applies for the protection of cardholder data (PAN, cardholder name, service code and expiration date) and sensitive authentication data (full track data from the magnetic stripe or equivalent data on the chip, CAV2/CVC2/CVV2/CID, and PIN/PIN block), from a payment card representing one of the founding PCI payment brands (American Express, Discover, JCB, MasterCard, or Visa).
Bank account data, such as branch identification numbers, bank account numbers, sort codes, routing numbers, etc., are not considered payment card data, and PCI DSS does not apply to this information.
However, if a bank account number is also a PAN or contains the PAN, then PCI DSS applies.
It should also be noted that some bank account numbers, such as IBAN (International Bank Account Number) may contain up to 10 PAN digits. If the number of PAN digits contained in an IBAN, or any other account number, is in excess of the truncation formats defined by the particular payment brand (see FAQ 1091), then PCI DSS applies.
Even if PCI DSS does not apply to a particular account number containing elements of PAN, it is strongly recommended that the account number be protected to avoid unauthorized persons from being able to derive the full PAN from the account number.