Fiscal Quarter (QN YYYY or YYYY QN) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching fiscal quarter (qn yyyy or yyyy qn), 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

# Fiscal Quarter (QN YYYY or YYYY QN)
# ReDoS-safe | RegexVault — Localization > Date Formats

import re

fiscal_quarter_qn_yyyy_or_yyyy_qn_pattern = re.compile(r'^(?:(Q[1-4])\s+((?:19|20)[0-9]{2})|((?:19|20)[0-9]{2})\s+(Q[1-4]))$')

def validate_fiscal_quarter_qn_yyyy_or_yyyy_qn(value: str) -> bool:
    return bool(fiscal_quarter_qn_yyyy_or_yyyy_qn_pattern.fullmatch(value))

# Example
print(validate_fiscal_quarter_qn_yyyy_or_yyyy_qn("Q1 2024"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Date Formats 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

Capture groups: 1=quarter (QN format), 2=year (QN format), 3=year (YQ format), 4=quarter (YQ format). Fiscal quarters may not align with calendar quarters — Q1 may start in January, April, July, or October depending on the company's fiscal year.