SEPA Creditor Identifier (CI) Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching sepa creditor identifier (ci), ported and verified for Python. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# SEPA Creditor Identifier (CI)
# ReDoS-safe | RegexVault — Finance > Bank Identifiers

import re

sepa_creditor_identifier_ci_pattern = re.compile(r'^[A-Z]{2}[0-9]{2}(?:ZZZ|[A-Z]{3})[A-Z0-9]{1,28}$')

def validate_sepa_creditor_identifier_ci(value: str) -> bool:
    return bool(sepa_creditor_identifier_ci_pattern.fullmatch(value))

# Example
print(validate_sepa_creditor_identifier_ci("DE98ZZZ09999999999"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Bank Identifiers category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Structure: 2-char country code + 2 check digits + 3-char creditor business code (ZZZ if not assigned) + national identifier. Check digits use same MOD-97 algorithm as IBAN.