Business registration numbers, untangled

Which number do you need?

1. Verifying a company exists: the state file number. Every entity in a state register carries the register's own number; Wisconsin's record fields include a 'DFI Entity ID# (not to be confused with FEIN)', the register's own warning against mixing the systems. Search the entity by name in the state register and the file number is on the record, free.
2. Tax and payroll: the federal EIN. The EIN is issued by the IRS, free, and used on returns, payroll and W-9s. The IRS's own page: 'Use this tool to get an EIN directly from the IRS in minutes for free.' There is no public federal directory of private companies' EINs; our EIN lookup page covers the official routes that do exist.
3. Cross-checking: registers that accept an EIN. Some state systems take the EIN as a search key, which lets you cross-walk the two systems: Maryland's entity search offers 'Employer Identification Number (EIN)' as a search-by option, and the Texas Comptroller's search takes 'the 9-digit Federal EIN'. Both rows are verified in the index with sources.

Why the US has no single company number

Company registration in the US is a state function: fifty-plus registers, each issuing its own identifiers, with the federal government issuing the EIN for tax only. A company operating in several states has a file number in each register where it is qualified plus one EIN, and no umbrella 'US company registration number' exists. When a foreign counterparty asks for your 'registration number', the useful answer is the home-state file number plus the state's name, and the EIN if the context is tax.

This is also why lookalike search sites flourish: there is no single official national search, so aggregators fill the gap with scraped data of uneven freshness. Every register in this index is the official state or federal source, which is the only place a number is authoritative.

Reading the numbers you find

State file numbers follow each register's own format; California's guidance, for example, explains that corporation numbers are searched with a leading 'C' and seven digits while LLC and partnership numbers run twelve digits. The EIN is always nine digits, conventionally written XX-XXXXXXX. A nine-digit number on a W-9 is the EIN; a number on a state certificate is the register's file number; the two never substitute for each other.

For public companies, one more identifier appears: the SEC's CIK number in EDGAR, which indexes the company's federal filings and, through them, its EIN. EDGAR's search is free and official.

Where each number is verified

Verify a state file number in the issuing state's register through the search links on our state pages. Verify an EIN against the company's own IRS paperwork or its SEC filings if public; no state register issues or certifies EINs. Where a register accepts EIN as a search input the state page says so with the official source quoted.

Questions people ask

Is a business registration number the same as an EIN?

No. The EIN is federal, issued by the IRS for tax. Registration numbers from a state register identify the entity in that state's records; Wisconsin's register explicitly warns its entity ID is 'not to be confused with FEIN'.

Does the US have a company registration number like other countries?

No single national number exists; registration is per state. The nearest equivalents are the home-state file number for legal identity and the EIN for tax identity.

How do I find a company's registration number?

Search the company by name in its state's official register; the record shows the file number free of charge. Our state pages link every official search directly.

Are these numbers confidential?

State file numbers are public record. The EIN is not published in a public federal directory, but it is not a secret either; it appears on public filings for SEC registrants and on paperwork a company hands its counterparties.

Cross-state lookups in the index

• EIN lookup with verified facts
• Registered agent lookup with verified facts