What is SSN Regex?

A Social Security Number (SSN) is a 9-digit identifier issued by the U.S. government. It follows this format:

AAA-GG-SSSS

Where:

• AAA = Area number

• GG = Group number

• SSSS = Serial number

Regex is commonly used to validate this structure in Java applications, APIs, and form inputs.

Java Regex Pattern for SSN

"^\\d{3}-\\d{2}-\\d{4}$"

Pattern Breakdown:

• ^ and $ → Anchors to ensure full-string match

• \\d{3} → Matches the area (3 digits)

• - → Hyphen separator

• \\d{2} → Group (2 digits)

• \\d{4} → Serial (4 digits)

This pattern validates properly formatted SSNs like 123-45-6789.

SSN Format Rules Beyond Regex

While the regex checks format, real SSNs must follow these rules:

• No zero groups: 000-12-3456, 123-00-4567, or 123-45-0000 are invalid.

• No prefix 666

• No numbers starting with 900–999

These filters help eliminate fake or improperly issued SSNs.

Java Code Example

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class SSNValidator {
    public static void main(String[] args) {
        String ssn = "123-45-6789";
        String regex = "^\\d{3}-\\d{2}-\\d{4}$";

        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(ssn);

        if (matcher.matches()) {
            System.out.println("Valid SSN");
        } else {
            System.out.println("Invalid SSN format");
        }
    }
}

Valid vs Invalid Examples

✅ 123-45-6789 – Valid

❌ 123456789 – Missing hyphens

❌ 12-345-6789 – Wrong grouping

❌ abc-de-ghij – Contains letters

Java Regex Flags (Quick Guide)

Use flags to modify how regex works:

• Pattern.CASE_INSENSITIVE – Match regardless of case

• Pattern.MULTILINE – Make ^ and $ work on each line

• Pattern.DOTALL – Allow . to match newlines

• Pattern.UNICODE_CASE – Handle Unicode characters

• Use matcher.find() loop for multiple matches

Pro Tips

• Never store SSNs in plaintext — always hash or encrypt

• Use input masks like ###-##-#### in forms

• Avoid placeholder SSNs like 123-45-6789 in live systems

• Regex checks format only — not whether the SSN is real or issued

• Pair frontend masking with backend regex for best results

Use Cases

• HR Systems – Validate employee details during onboarding

• Finance Apps – Prevent invalid IDs for secure processing

• Govt Portals – Enforce correct formats in public data forms

• Data Cleanup – Detect and fix malformed SSNs in databases

Combine with These Tools

• Email Regex Java Validator – Validate user emails in the same form.

• Phone Number Regex Java Validator – Validate U.S. phone numbers alongside SSNs.

• Java Regex Tester – Experiment with custom SSN patterns.