Social Security Number Validation Regex (US)

Validate US Social Security Numbers in XXX-XX-XXXX format with validation rules excluding invalid number ranges using regex pattern.

Pattern Breakdown

^(?!000|666|9\d\d)\d{3}-(?!00)\d{2}-(?!0000)\d{4}$

Components

Detailed Breakdown

• (?!000|666|9\d\d) - Negative lookahead for area number:
  • 000 - Invalid area number
  • 666 - Invalid area number
  • 9\d\d - Invalid area numbers 900-999
• (?!00) - Negative lookahead: group number cannot be 00
• (?!0000) - Negative lookahead: serial number cannot be 0000

Examples

Valid:

• 123-45-6789
• 001-23-4567 (area 001 is valid)
• 555-12-3456
• 123-01-2345 (group 01 is valid)

Invalid:

• 000-12-3456 (area 000 is invalid)
• 666-12-3456 (area 666 is invalid)
• 900-12-3456 (area 900-999 are invalid)
• 123-00-3456 (group 00 is invalid)
• 123-45-0000 (serial 0000 is invalid)
• 123456789 (missing hyphens)
• 123-45-67890 (too many digits)

Implementation

JavaScript

const ssnRegex = /^(?!000|666|9\d\d)\d{3}-(?!00)\d{2}-(?!0000)\d{4}$/;
ssnRegex.test('123-45-6789'); // true
ssnRegex.test('001-23-4567'); // true
ssnRegex.test('000-12-3456'); // false (invalid area)
ssnRegex.test('666-12-3456'); // false (invalid area)
ssnRegex.test('123-00-3456'); // false (invalid group)

Python

import re
ssn_regex = r'^(?!000|666|9\d\d)\d{3}-(?!00)\d{2}-(?!0000)\d{4}$'
bool(re.match(ssn_regex, '123-45-6789'))  # True
bool(re.match(ssn_regex, '001-23-4567'))  # True
bool(re.match(ssn_regex, '000-12-3456'))  # False (invalid area)
bool(re.match(ssn_regex, '666-12-3456'))  # False (invalid area)

Go

ssnRegex := regexp.MustCompile(`^(?!000|666|9\d\d)\d{3}-(?!00)\d{2}-(?!0000)\d{4}$`)
ssnRegex.MatchString("123-45-6789") // true
ssnRegex.MatchString("001-23-4567") // true
ssnRegex.MatchString("000-12-3456") // false (invalid area)

Limitations

1. Format only: Validates format and invalid ranges, not actual SSN validity
2. No database check: Doesn't verify if SSN is actually issued
3. No historical validation: Doesn't check against historical invalid ranges
4. Security: SSNs are sensitive PII - handle with extreme care
5. No unformatted support: Requires hyphens (add pattern for unformatted if needed)

When to Use

• SSN format validation in forms
• Initial format checking
• When you need to verify SSN structure
• Input validation for SSN fields

For production, consider:

• Supporting unformatted SSNs: ^(?!000|666|9\d\d)\d{3}-?(?!00)\d{2}-?(?!0000)\d{4}$
• Masking SSNs in display (show only last 4 digits)
• Encrypting SSNs in storage
• Complying with privacy regulations (HIPAA, etc.)
• Never storing full SSNs unless absolutely necessary
• Using specialized SSN validation libraries