Authoritative Data Source & Methodology

This validator checks SSN formats against the allocation data published by the Social Security Administration (SSA). The core of our logic relies on the public SSN Area Number allocation list, which details which Area Numbers (the first 3 digits) were assigned to which states and territories from 1936 until 2011.

All validation checks are based strictly on this public data. We do not have access to any private database.

How SSN Validation Works

A Social Security Number has three parts: NNN-GG-SSSS. Our validator performs a series of checks on these parts in order:

  1. Format Check: Verifies the input is 9 digits (after stripping any dashes).
  2. Area Number (NNN) Check:
    • Ensures the Area Number is not 000, 666, or in the 900-999 range, as these were never assigned.
    • Checks the number against the SSA's allocation list to find its corresponding state and issuance period.
  3. Group Number (GG) Check: Ensures the Group Number is not 00.
  4. Serial Number (SSSS) Check: Ensures the Serial Number is not 0000.

If a number passes all these checks, it is considered to have a valid format. If it fails any check, it is invalid. Note: Since June 2011, the SSA has "randomized" SSN issuance. New SSNs no longer follow the geographic allocation, but this tool can still validate their format against invalid patterns.

Glossary of Terms

  • SSN (Input): The 9-digit number to be validated.
  • Area Number (NNN): The first 3 digits. Historically, this indicated the state or territory where the card was issued.
  • Group Number (GG): The middle 2 digits. These were issued sequentially within each Area.
  • Serial Number (SSSS): The last 4 digits. These were also issued sequentially within each Group.
  • Validation Status (Output): The result of the check, either "Valid Format" or "Invalid Format".
  • Issuance Info (Output): For valid pre-2011 numbers, this shows the state/territory and time frame the Area Number was allocated to.

How It Works: A Step-by-Step Example

Let's validate the number 042-42-1234:

  1. Format Check: The input has 9 digits. (Pass)
  2. Area Number (NNN) Check: The Area Number is 042.
    • It is not 000, 666, or 900+. (Pass)
    • Looking up 042 in the SSA data, we find it was allocated to New York between 1951-1962.
  3. Group Number (GG) Check: The Group Number is 42. It is not 00. (Pass)
  4. Serial Number (SSSS) Check: The Serial Number is 1234. It is not 0000. (Pass)

Final Result: The tool reports "Valid Format" and provides the issuance details: "Issued in New York (1951-1962)."

Frequently Asked Questions

Does this tool check if an SSN is 'real' or 'active'?

No. This is a format validator, not a verification service. It checks if the number's structure (Area, Group, Serial) is valid according to historical data from the Social Security Administration (SSA). It CANNOT tell you if the SSN is assigned to a person, active, or exists in the SSA's database. Only official government services like E-Verify can do that.

Is it safe to enter an SSN here? Do you store my data?

This tool is 100% safe and secure. All validation logic runs entirely within your web browser (client-side). The number you enter is NEVER sent to our server, stored, or logged in any way. You can verify this by disconnecting your internet after the page loads; the tool will still work.

What is the 'State of Issuance'?

Before 2011, the first three digits (Area Number) of an SSN indicated the state or territory where the card was applied for. This was not necessarily the person's state of birth. Our tool uses this historical data to show you where the number was allocated. SSNs issued after 2011 are 'randomized' and no longer have this geographic meaning.

Why does my number show as 'Invalid Area Number'?

The SSA never assigned certain Area Numbers (the first 3 digits). This includes 000, 666, and any number from 900 to 999. If your number starts with one of these, it is not a validly formatted SSN.

What does 'Invalid Group' or 'Invalid Serial' mean?

Within each Area Number, the SSA also invalidated certain Group Numbers (middle 2 digits) and Serial Numbers (last 4 digits). For example, a Group Number of 00 or a Serial Number of 0000 is never valid. Our tool checks for these known invalid patterns.

My valid SSN was issued after 2011. What will this tool show?

For SSNs issued after June 2011, the tool will still validate the format. If it doesn't start with 000, 666, or 900+, and doesn't contain 00 (Group) or 0000 (Serial), it will be marked as "Valid Format". It will also note that this Area Number was part of the post-2011 randomization pool.

Tool developed by Ugo Candido. Content and methodology reviewed by the CalcDomain Editorial Board.
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