An EIN (Employer Identification Number), also called a Federal Tax Identification Number, is a 9-digit number the IRS assigns to businesses for tax purposes. It is written as XX-XXXXXXX.

What does the EIN prefix mean?

The first two digits are the prefix, historically indicating which IRS campus assigned the number. Since 2001 many are assigned online or by a centralized process, but only a known set of prefixes is ever used.

Does a valid prefix mean the EIN is real?

No. A valid prefix and format mean the EIN is plausibly issuable. Confirming a specific EIN belongs to a specific entity requires the IRS or a paid TIN-matching service.

Is there a check digit on an EIN?

No. Unlike some national IDs, the EIN has no checksum digit. The only offline checks are the 9-digit format and a valid two-digit assignment prefix.

Is my EIN sent anywhere?

No. All checks run locally in your browser. The EIN never leaves your device.

US EIN Validator — Gera Tools

A US Employer Identification Number (EIN) is the 9-digit Federal Tax Identification Number the IRS issues to businesses, written as XX-XXXXXXX. There is no checksum on an EIN, but the IRS only ever uses a fixed set of two-digit prefixes that map to its campus-assignment system. This free validator checks the format and confirms the prefix is on that list — useful for accounts-payable teams pre-screening vendor records.

How it works

The validation has two parts:

Format check — strip the dash and confirm exactly 9 digits remain, in the XX-XXXXXXX layout (2-digit prefix + 7-digit serial).
Prefix check — the first two digits must be in the IRS published prefix set. Valid prefixes include 01–06, 10–16, 20–27, 30–48, 50–68, 71–77, 80–88, 90–95, and 98–99, among the documented campus and internet/SS-4 assignment ranges. Prefixes like 07, 08, 09, 17–19, 28, 29, and 49 are not assigned.

If the prefix is on the list and the format is correct, the EIN is structurally plausible.

Example

Validate 12-3456789 → 9 digits, prefix 12. Prefix 12 is an active Internet/Andover-style assignment prefix, so the EIN is format- and prefix-valid.

Tips and notes

A valid format and prefix do not confirm the EIN was actually issued to a specific business. For binding verification, use the IRS TIN matching program or request the entity’s CP-575/147C letter. All checks here run locally — your EIN never leaves the browser.