The correct EIN format is nine digits written as XX-XXXXXXX: two digits, a hyphen, then seven digits. The IRS assigns this Employer Identification Number to businesses, nonprofits, trusts, and estates as a federal tax ID, and it works for an entity the way a Social Security number works for a person.1Internal Revenue Service. Employer Identification Number Federal regulations set that two-then-seven layout as the standard form of the number.2eCFR. 26 CFR 301.6109-1 – Identifying Numbers
What the Two-Digit Prefix Means
The first two digits are called the EIN prefix. They once pointed to a geographic region, but the IRS now assigns them based on the campus or processing system that handled the application. Online applications draw from a dedicated block of prefixes; paper and fax applications receive a prefix tied to the IRS campus of record.3Internal Revenue Service. 21.7.13 Assigning Employer Identification Numbers
Because the prefix reflects how and where the number was issued rather than where the business operates, you cannot tell a company’s location just by reading its EIN. A business headquartered in Texas may carry a prefix that has nothing to do with Texas, depending on which IRS system generated the number.
The Seven-Digit Serial
The remaining seven digits after the hyphen are the serial portion of the number, unique to the entity. Combined with the prefix, they produce a nine-digit identifier that stays with that entity for life. The IRS does not reuse EINs, and it cannot cancel one once it has been assigned; the number will always belong to that entity even after the account is closed.4Internal Revenue Service. If You No Longer Need Your EIN
How EIN Format Differs From a Social Security Number
Both numbers contain nine digits, but they are grouped differently on purpose. A Social Security number uses a three-two-four pattern (XXX-XX-XXXX). An EIN uses two-seven (XX-XXXXXXX). The IRS chose the different grouping so data-entry errors between the two are easier to catch.3Internal Revenue Service. 21.7.13 Assigning Employer Identification Numbers
If a number you are looking at breaks into three-two-four, it is being written as an SSN. If it breaks into two-seven, it is being written as an EIN. The digit count is the same; the placement of the hyphen carries the meaning.
Spotting a Valid EIN
A properly formatted EIN has exactly nine digits and a single hyphen after the second digit. Anything longer, shorter, or hyphenated in a different spot is not in the IRS format. Documents sometimes strip the hyphen entirely and show only the nine digits, which is still the same number; the hyphen is a display convention, not part of the digits themselves.
Format alone does not confirm that a number is real or that it belongs to the entity claiming it. It only tells you the number is written the way an EIN should be written. Verification of the underlying number goes through the IRS, not through pattern-matching.
Where to Find Your EIN in Its Correct Form
The original source is Notice CP 575, the EIN confirmation letter the IRS mails to the business address shortly after the number is first assigned. That letter lists the EIN in its official format along with the entity’s legal name, filing address, and the tax returns the business is required to file.
If the confirmation letter is gone, the number will appear on prior-year federal tax returns, bank account opening paperwork, and state or local business license applications. When none of those turn up, an authorized person can call the IRS Business and Specialty Tax Line at 800-829-4933; the representative will verify identity and relationship to the entity before disclosing the number.1Internal Revenue Service. Employer Identification Number
When Your EIN Stays the Same and When It Changes
The format of the number never changes, but the number itself sometimes does. Routine updates do not require a new EIN. Changing your business name, adding a new location, or switching your address does not produce a new number, and neither does a corporation or partnership filing for bankruptcy.5Internal Revenue Service. When to Get a New EIN
Certain structural changes do create a legally new entity that needs its own EIN. The triggers vary by entity type:5Internal Revenue Service. When to Get a New EIN
- Sole proprietors who incorporate, form a partnership, or file for bankruptcy.
- Partnerships that incorporate, dissolve and start a new partnership, or whose partner takes over as a sole proprietor.
- Corporations that receive a new charter from the secretary of state, form a subsidiary, convert to a partnership or sole proprietorship, or merge to create a new corporation. A surviving corporation after a merger keeps its existing EIN.
- LLCs that terminate and form a new corporation or partnership, or single-member LLCs that must begin filing employment or excise tax returns.
Each new EIN issued in these situations will follow the same XX-XXXXXXX format, with a fresh prefix reflecting the campus or system that assigned it.
Updating the Information Behind Your EIN
The number and its format stay put through most changes, but the IRS still needs current information on the entity behind it. Changes to the business address, location, or responsible party get reported on Form 8822-B, and changes to the responsible party carry a strict 60-day reporting deadline.6Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party – Business
Missing the deadline does not draw a direct penalty, but if the IRS does not have your current responsible party on file, notices of deficiency or demand letters may go to the wrong person. You would never see them, and penalties and interest would keep accruing on any unpaid balance.7IRS. Form 8822-B Change of Address or Responsible Party – Business Whenever a founder leaves or a new officer takes control, file the form right away.