# Look Up a Company EIN > Check whether a nine-digit number is a well-formed EIN, and find out where to look for the company behind one. Canonical: https://corpoapi.com/checks/ein-lookup Type an EIN and the check reports whether the number is the right shape and whether the prefix is one the US tax authority uses. It states the limit: an EIN is not published against a company in any register we can read, so this cannot tell you who the number belongs to. It tells you where to look instead. ## What the check reads - **Nine digits** Spaces and hyphens are stripped before the count. A number with letters in it fails, because an EIN has no letters. - **The prefix** The first two digits are checked against the ranges the US tax authority assigns to its processing offices. A number outside every range has never been issued. - **What this does not check** Whether the number was ever issued, to whom, and whether the business is still trading. None of that is in a public source we can read. - **Individual taxpayer numbers** An ITIN, an SSN and an EIN share a nine-digit shape but mean different things. This check is written for an EIN and does not claim to validate the others. ## Where the data comes from - [IRS, apply for an EIN](https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online): The US tax authority, which issues an EIN and explains what one is for. - [IRS Internal Revenue Manual 3.11.180](https://www.irs.gov/irm/part3/irm_03-011-180r): The office code ranges the IRS assigns. The check reads the first two digits against this list. ## Worked examples ### Nine digits, with a prefix the US tax authority uses Input: `12-3456789` - **Nine digits**: Yes - **Prefix 12 assigned**: Yes, Andover - **Verdict**: Well formed - **Business behind it**: Not knowable from an EIN This is a format example, written to show the check working. It is not a real business, and the check cannot tell you whether any particular EIN was ever issued. ### Nine digits, with a prefix the US tax authority never assigns Input: `07-1234567` - **Nine digits**: Yes - **Prefix 07 assigned**: No - **Verdict**: Not an issued EIN - **Reason**: The assigned ranges skip 07 The ranges run 01 to 06 and then 10 to 16, so 07 is in the gap. A discarded or mistyped number usually fails here. ### One digit short Input: `12345678` - **Digits**: 8 - **Needed**: 9 - **Verdict**: Not an EIN The most common mistake is a dropped digit, usually at the start, where the leading zero is easy to lose. ## The nine digits and the prefix An EIN is nine digits, usually written with a hyphen after the first two. The first two are a code for the US tax authority office that issued it, and the US tax authority only assigns certain code ranges. A number with a valid shape and an assigned prefix is a number the US tax authority could have issued. Anything else is not an EIN. - Nine digits, hyphen optional - Prefix checked against the ranges the US tax authority assigns - Names the failing part instead of returning a bare rejection ## No register publishes an EIN against a company An EIN belongs to the US tax authority and is used for tax administration. The public registers we read, one per state, publish a state company number instead. Nothing joins the two in the open, so no honest tool can turn an EIN into a business name. The tool points you at a company search by name instead. - A well-formed EIN does not identify a business - A state company number is a different identifier - Search by name when the EIN is all you have ## Search the register by name If you have a name, a state and a rough idea of what the company does, a registry search usually resolves it. Our free company search runs the same lookup as the API and returns the matched entity with its state company number, status and registered address. - Fuzzy name matching, accent aware - Exact resolution when you have the state number - Results carry the state and the register's own number ## FAQ ### Can you look up who owns an EIN? No, and no public source we can read lets us. The US tax authority issues an EIN for tax administration and does not publish it against a company. The registers we read publish state company numbers instead, and nothing available to us joins the two. The honest next step is a register search by company name. ### Why does an AI tool sometimes answer this question? A language model will produce a plausible company name for almost any number, so a plausible name is not an answer. If a tool gives you a business against an EIN, ask it which register it read, because there is no register that carries one. ### What is the difference between an EIN and a company number? An EIN comes from the US tax authority and identifies a taxpayer. A company number comes from a state and identifies a registered entity. A single business normally has both, and they look nothing alike. ### Does the prefix tell me which state the business is in? No. The prefix identifies the US tax authority office that processed the application, and filing is organised by where the business was formed and where it operates. Two businesses in the same state routinely carry different prefixes. ### Is an EIN the same as a DUNS number? No. An EIN is issued by the US tax authority for tax. A DUNS number is issued by Dun and Bradstreet for business identification, and it is a nine-digit number with no relation to the EIN. We have a separate check for the DUNS format. ### How do I find the company if the EIN is all I have? Try the free company search with whatever else you know: the trading name, the state, or the registered agent. A name search returns ranked candidates with their state numbers, and once you have a state number the record resolves exactly.