Canadian Transit Number Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching canadian transit number, 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

# Canadian Transit Number
# ReDoS-safe | RegexVault — Finance > Bank Identifiers

import re

canadian_transit_number_pattern = re.compile(r'^[0-9]{5}-?[0-9]{3}$')

def validate_canadian_transit_number(value: str) -> bool:
    return bool(canadian_transit_number_pattern.fullmatch(value))

# Example
print(validate_canadian_transit_number("10000-002"))  # 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

Transit number format: BBBBBIII where BBBBB is branch number and III is institution number (002=TD, 003=RBC, 004=Scotiabank, 006=NBC, 010=CIBC, 016=HSBC, 219=ATB). Used with 7-12 digit account number.