Dutch Postcode (Postcode) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching dutch postcode (postcode), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. 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

# Dutch Postcode (Postcode)
# ReDoS-checked | RegexVault — Localization > Postal Codes

import re

dutch_postcode_postcode_pattern = re.compile(r'^([1-9][0-9]{3})\s?(?!SS|SD|SA)[A-Z]{2}$')

def validate_dutch_postcode_postcode(value: str) -> bool:
    return bool(dutch_postcode_postcode_pattern.fullmatch(value))

# Example
print(validate_dutch_postcode_postcode("1234 AB"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and has been checked for ReDoS risk. 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

The letter combinations SA, SD, SS are officially excluded. Some unofficial sources also exclude combinations that form offensive words in Dutch. The space is optional but conventionally present.