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SSN Validator

Finance & Global IDs

Validate whether a US Social Security Number follows the official format and passes SSA range rules. Browser-only — your SSN is never transmitted.

Reviewed by the thecalcu.com team · Last updated July 27, 2026

What is a SSN?

The SSN Validator checks whether a United States Social Security Number (SSN) follows the official 9-digit format defined by the Social Security Administration (SSA), including the known exclusion rules that the SSA has never assigned. An SSN is the most widely used personal identifier in the United States, it appears on tax returns, credit applications, bank accounts, and government records.

The format is AAA-GG-SSSS: three groups separated by hyphens, totalling 9 digits. The three groups are the area number (first 3 digits), the group number (middle 2 digits), and the serial number (last 4 digits). This validator accepts both hyphenated (123-45-6789) and unhyphenated (123456789) input.

Beyond the basic 9-digit length check, the validator applies the SSA's documented exclusion rules: area 000, 666, and 900–999 are never assigned; group 00 is never assigned; serial 0000 is never assigned. It also flags two publicly known invalid SSNs that appeared in historical SSA sample materials.

This tool is equivalent to PAN Number Validator and Aadhaar Number Validator for the Indian context, all three check document number formats for their respective countries.

Why Use an SSN Validator?

SSNs are entered in US tax forms (W-9, W-4, 1099), mortgage and credit applications, background check authorisations, and healthcare enrollment forms. A single transposed digit or a number that violates SSA exclusion rules will cause the downstream process to fail, tax filings get rejected, background checks return no match, and credit bureaus cannot locate the individual's record.

Developers building US-facing forms, HR platforms, or tax preparation software need a reliable client-side validator that goes beyond a simple 9-digit check. This tool documents all the exclusion rules that apply.

Who Should Use This Validator?

US residents completing tax or financial forms, A quick check before submitting a tax return or credit application catches transposition errors that would otherwise require corrections weeks later.

HR and payroll teams, Companies collecting SSNs from new employees for W-4 and payroll registration need a format check at the point of data collection to avoid IRS filing errors.

Developers building US-facing applications, Any web form that collects SSNs for employment, tax, or financial purposes should validate format on the client side before sending to the backend. This tool documents the exact rules to implement.

Background check and identity verification teams, Investigators and screeners who receive SSNs from applicants can do a structural pre-check before submitting to a verification service, reducing wasted queries for obviously invalid numbers.

Freelancers and international contractors working with US clients, Understanding the SSN format helps international workers distinguish between a real SSN request and a scam, and clarifies when to request an ITIN instead.

What Insights Does the SSN Validator Give You?

A valid result confirms that the SSN passes all five structural checks: correct length (9 digits), area not 000, area not 666, area not 900–999, group not 00, and serial not 0000. The details section shows the three components, area, group, and serial, split out separately so you can visually verify each part.

An invalid result names the specific rule that failed, which is more actionable than a generic "invalid SSN" message when correcting data-entry errors in a batch.

How to use this SSN calculator

  1. Type or paste the SSN into the input field. You can enter it with hyphens (123-45-6789) or without (123456789), both formats are accepted.
  2. The result updates automatically as you type, no button press needed.
  3. Check the Valid or Invalid badge.
  4. If Invalid, read the error message to identify the specific rule that failed.
  5. If Valid, check the details for the area, group, and serial breakdown and the list of checks passed.
  6. To validate a different SSN, clear the field and enter the new value.

Formula & Methodology

Format rule: An SSN must satisfy all of the following:

1. Exactly 9 digits (hyphens are stripped before checking)
2. Area (digits 1–3): not 000, not 666, not 900–999
3. Group (digits 4–5): not 00
4. Serial (digits 6–9): not 0000

Regular expression (after stripping hyphens): /^\d{9}$/ with the additional range exclusions above.

Valid example: 123-45-6789, area 123 (not excluded), group 45 (not 00), serial 6789 (not 0000).

Invalid examples:
- 000-45-6789, area 000 is excluded
- 666-45-6789, area 666 is excluded
- 900-45-6789, area 900–999 is excluded
- 123-00-6789, group 00 is excluded
- 123-45-0000, serial 0000 is excluded
- 078-05-1120, publicly advertised sample card number, explicitly invalid

Related Tools

You may also find these useful: Credit Card Number Validator.

Frequently Asked Questions

A Social Security Number (SSN) is a 9-digit identifier issued by the US Social Security Administration (SSA) to US citizens, permanent residents, and certain non-immigrants with authorisation to work in the United States. Originally created in 1936 to track earnings for Social Security benefit purposes, the SSN has become a general-purpose national identifier used for tax filing, credit applications, employment verification, and government services.
An SSN is exactly 9 digits divided into three groups: a 3-digit area number, a 2-digit group number, and a 4-digit serial number. It is conventionally written with hyphens as AAA-GG-SSSS (for example, 123-45-6789). The area number historically identified the state where the application was filed, but since the Randomisation program began in June 2011, new SSNs are assigned randomly and the area number no longer encodes geography.
The SSA never assigns an SSN where: the area (first 3 digits) is 000, 666, or any value from 900 to 999; the group number (middle 2 digits) is 00; or the serial number (last 4 digits) is 0000. These exclusions are official SSA policy and have applied since the system was created. An SSN that violates any of these rules could not have been legitimately issued.
No. This tool checks only whether the SSN follows the correct 9-digit format and passes the SSA's known exclusion rules (no 000/666/900-999 area, no 00 group, no 0000 serial). It does not query SSA databases and cannot confirm whether the number is assigned, active, or belongs to any individual. Only the SSA and authorised entities (such as employers using E-Verify) can perform a live SSN verification.
Yes. Validation runs entirely in your browser. Your SSN is never transmitted to any server, stored in a database, or shared with any third party. You can verify this by disconnecting from the internet before using the tool, it will continue to work normally. That said, exercise the same caution you would with any sensitive number: avoid entering it on a shared or untrusted device.
Before June 2011, SSNs were issued based on the state where the application was made, the area number encoded the state. From June 2011 onward, the SSA switched to randomised assignment, where area, group, and serial numbers are assigned without geographic meaning. This was done to extend the lifespan of the SSN pool and reduce identity theft based on predictable number ranges. SSNs issued before 2011 may still follow the old geographic pattern.
078-05-1120 is a famous invalid SSN that appeared on a sample Social Security card printed by a wallet manufacturer in 1938. The card was distributed inside wallets sold in department stores, and many people mistakenly assumed it was their own SSN. At its peak, over 40,000 people were using that number as their own. The SSA explicitly retired it, and this validator flags it as a known invalid number.
Legitimately, no. The SSA's system is designed to assign each SSN exactly once. However, identity theft, database errors, and fraudulent use have resulted in cases where the same number appears associated with multiple individuals in non-SSA databases. The SSA itself maintains the authoritative record of which SSN was legitimately issued to which person.
The 900-999 range was historically reserved for taxpayer identification numbers (ITINs) assigned by the IRS and other non-SSA purposes in some states. These numbers resemble SSNs in format but are not Social Security Numbers. The SSA has never assigned a legitimate SSN with an area number of 900 or higher. Encountering such a number in an SSN field is a strong signal of either a data entry error or fraudulent use.
An ITIN is a 9-digit number issued by the IRS to individuals who need a US taxpayer ID but are not eligible for an SSN, primarily non-resident aliens and their dependants. ITINs always begin with the digit 9 and have a specific format (9XX-XX-XXXX with certain group number ranges). Because ITINs start with 9, this validator correctly identifies them as not being valid SSNs. ITINs are used only for tax filing purposes, not for Social Security benefits or employment eligibility.
Non-US citizens who are not authorised to work in the US do not have an SSN. If a US entity requires an SSN for tax purposes (such as freelance or investment income), you may instead apply for an ITIN from the IRS using Form W-7. If a form requires an SSN for employment verification, your employer should use the E-Verify system. Never fabricate or borrow an SSN, doing so is a federal offence under 42 USC § 408.
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