SSN Regex Java Validator

What is SSN Regex?

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

AAA-GG-SSSS

Where:

• AAA is the area number

• GG is the group number

• SSSS is the serial number

  
  

Regex is commonly used to validate this structure in input forms, APIs, and databases.

Java SSN Regex Pattern

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

Explanation:

• ^ and $ → Ensure the string matches the pattern from beginning to end

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

• - → Matches the hyphen separator

• \\d{2} → Matches 2 digits (group number)

• \\d{4} → Matches 4 digits (serial number)

  
  

This pattern validates only properly formatted SSNs (e.g., 123-45-6789).

SSN Numbering Rules and Restrictions

While the regex above ensures the format is correct, a valid Social Security number must also follow some additional rules:

• No all-zero groups: None of the digit groups (the area, group, or serial parts) can be all zero. For example, numbers like 000-12-3456, 123-00-4567, or 123-45-0000 are not valid.

• Disallowed prefixes: Numbers cannot start with 666.

• Range limitations: An SSN cannot begin with any number in the 900–999 range.

These restrictions help further weed out invalid or potentially suspicious SSNs, building on top of the basic pattern match.

How Regex Flags Work

When working with regex in Java (and most other languages), various flags can enhance or modify how your pattern matches strings. Here’s what some of the most common flags do:

• g (global): Searches for all matches in the input, not just the first one. In Java, this behavior is achieved by repeatedly calling matcher.find() in a loop.

• i (ignore case): Makes your regex case-insensitive, matching both uppercase and lowercase letters. In Java, this is equivalent to using Pattern.CASE_INSENSITIVE.

• m (multiline): Allows ^ and $ to match the start and end of each line, not just the start and end of the entire string. Use Pattern.MULTILINE in Java for this effect.

• s (dotAll): Lets the dot . match newlines (``) as well as all other characters. Java uses Pattern.DOTALL to enable this.

• u (unicode): Treats pattern strings as Unicode; helps with matching characters outside the basic ASCII set. Java’s Pattern.UNICODE_CASE flag covers this area.

• y (sticky): Attempts to find a match starting exactly at the position specified in the target string. While JavaScript supports this natively, in Java you can control matching starting positions with the Matcher class methods.

Understanding and combining these flags appropriately ensures your SSN regex validator works exactly as intended, no matter the input or use case.

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");
        }
    }
}

Examples

• 123-45-6789 → Valid

• 123456789 → Missing hyphens

• 12-345-6789 → Invalid groupings

• abc-de-ghij → Contains non-numeric characters

Pro Tips

• Don’t store SSNs in plaintext. Always encrypt or hash when saving to databases.

• If accepting SSNs from international users, ensure your regex restricts entries to valid U.S. formats.

• Use input masks on front-end forms to guide users toward the correct format (###-##-####).

• Avoid using placeholder SSNs like 123-45-6789 in production data—they’re publicly known and insecure.

• The regex validates format only — not whether the SSN is officially issued.

Use Cases

• HR Systems: Ensure employee SSNs are correctly formatted during onboarding.

• Financial Services: Validate identity before processing loans or payments.

• Government Forms: Automatically reject improperly formatted SSNs.

• Databases: Clean up and standardize SSN fields.

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.