I want to catch structurally invalid IBANs during user signup so I can prompt corrections immediately.

This feature validates the structure of an IBAN at the moment a user enters it during signup. It helps users correct formatting issues immediately, reducing failed submissions and follow-up support.

This feature performs real-time structural validation of IBAN values during user signup to identify invalid entries as early as possible. When a user types or submits an IBAN, the system checks that it matches expected IBAN structure rules, such as length, allowed characters, and the standard IBAN checksum validation. If the value is structurally invalid, the signup flow can present a clear, actionable message prompting the user to correct the IBAN before proceeding. This reduces friction caused by later-stage rejections and prevents incomplete or inaccurate bank details from entering the system. It also improves data quality by ensuring only structurally valid IBANs are accepted at the point of capture. The validation is intended to be lightweight and immediate, focusing on structural correctness rather than verifying account ownership or bank availability. The feature is useful in any onboarding scenario where IBANs are collected for payouts, direct debits, or billing setup. It can be paired with field-level UI guidance (such as inline error states) to help users fix common mistakes like missing characters or incorrect spacing. As a result, teams can expect fewer failed onboarding attempts and fewer support tickets related to invalid bank detail entry.