Authoritative Source and Methodology

This validator checks an EIN against the formatting rules and prefix list provided by the Internal Revenue Service (IRS).

All calculations are based strictly on the formatting rules and data provided by this source. This tool validates format, it does not verify existence. It cannot confirm if an EIN is active, issued, or belongs to a specific company.

The Validation "Formula" Explained

EIN validation is a logical algorithm, not a single mathematical formula. To be considered a valid format, an EIN must pass three checks. The logic can be expressed symbolically:

Let $E_s$ be the input string (EIN).
Let $E_c$ be the "cleaned" string, $E_s$, with all non-numeric characters removed.
Let $P$ be the prefix of $E_c$, $P = \text{substring}(E_c, 0, 2)$.
Let $S$ be the set of valid IRS prefixes: $S = \{10, 12, 13, 14, 16, 20, 21, \dots, 99\}$.
$\text{ValidFormat} = (\text{length}(E_c) = 9) \land (P \in S)$

Glossary of Variables

  • EIN (Employer Identification Number): A 9-digit number assigned by the IRS to identify business entities. Also known as a Federal Employer Identification Number (FEIN).
  • Input EIN: The 9-digit number provided by the user. The hyphen ($XX-XXXXXXX$) is optional.
  • Prefix ($P$): The first two digits of the EIN. These digits historically indicated the IRS campus where the number was issued.
  • Valid Prefix Set ($S$): The complete list of 2-digit prefixes currently recognized by the IRS as valid. Prefixes like 00, 07-09, or 15 are not valid.
  • Validation: The process of checking if a number's *format* is correct (9 digits, valid prefix).
  • Verification: The process of checking if a number exists in an official database (like the IRS master file). This tool performs validation, not verification.

How It Works: A Step-by-Step Example

Let's test two different numbers to see the logic in action.

Case 1: Valid Format Input

  • Input ($E_s$): 45-1234567
  • Step 1 (Clean): The hyphen is removed. $E_c = 451234567$.
  • Step 2 (Length Check): $\text{length}(E_c)$ is 9. (Pass)
  • Step 3 (Prefix Check): The prefix $P$ is '45'. Is '45' in the valid prefix set $S$? Yes. (Pass)
  • Result: Valid Format.

Case 2: Invalid Format Input

  • Input ($E_s$): 071234567
  • Step 1 (Clean): No characters to remove. $E_c = 071234567$.
  • Step 2 (Length Check): $\text{length}(E_c)$ is 9. (Pass)
  • Step 3 (Prefix Check): The prefix $P$ is '07'. Is '07' in the valid prefix set $S$? No. (Fail)
  • Result: Invalid Format. The prefix '07' is not assigned by the IRS.

Frequently Asked Questions

What is an EIN used for?

An EIN is used by the IRS to identify business entities for tax reporting. It is also required for many other business functions, such as opening a business bank account, applying for business licenses, and processing payroll.

How is an EIN different from a Social Security Number (SSN)?

An EIN is for business entities (corporations, partnerships, LLCs, sole proprietorships with employees, etc.), while an SSN is for individuals (citizens, permanent residents). They share a 9-digit format but are distinct identifiers.

Does this tool check if a company is legitimate or real?

No. This tool only performs format validation. It cannot perform verification. A "Valid Format" result does not mean the EIN is active, issued, or belongs to the company you think it does. It only means the number's structure is correct.

How can I find a company's EIN?

A company's EIN may be found on its official tax documents (like a W-9 or 1099), payroll statements, or business credit reports. Publicly traded companies often list it in their SEC filings. For private companies, you may need to use a paid KYB (Know Your Business) verification service.

How do I apply for an EIN?

You can apply for an EIN for free directly on the official IRS.gov website. The online application process is the fastest and provides the EIN immediately upon completion.

Tool developed by Ugo Candido. Content verified by the CalcDomain Editorial Board.
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