EIN, in plain English
An Employer Identification Number, usually called an EIN, is a nine-digit number issued by the Internal Revenue Service to identify a business or other entity for federal tax administration. Think of it as a federal tax account number for the entity, not as a business license and not as proof that the company is in good standing with a state.
An EIN stays attached to the entity's federal tax account. It is commonly requested when a company opens a bank account, runs payroll, files federal business tax returns, works with payment processors, or completes tax documents for customers and vendors.
Who needs an EIN
The IRS says an EIN is required in a number of common situations, including when a business has employees, operates as a partnership or corporation, or must file certain employment, excise, or withholding tax returns. LLCs frequently obtain EINs as well, although the federal tax treatment of an LLC depends on its number of owners and any tax elections it makes.
A sole proprietor with no employees may not always need an EIN for federal tax purposes, but the IRS allows a business to request one for legitimate banking or state-tax reasons. Banks, payroll providers, marketplaces, and state agencies may have their own onboarding requirements.
When to apply
If you are forming a legal entity such as an LLC or corporation, form the entity with the state first and then apply for the EIN using the entity's exact legal name. That order reduces mismatches between state records, IRS records, bank records, and tax filings.
Apply early enough that the EIN is available before you need to open accounts or run payroll, but do not create duplicate EIN applications for the same entity. The IRS specifically recommends using only one application method for each entity.
What an EIN does not replace
- State formation documents, such as articles or a certificate of incorporation.
- A state sales-tax permit, payroll registration, or local business license.
- A registered agent where one is required.
- A personal SSN or ITIN when a form specifically asks for an individual's taxpayer identification number.
- Good-standing or annual-report obligations with the state.
A clean EIN setup checklist
Keep the IRS EIN assignment notice with the permanent company record. Make sure the legal name and address used with banks, payroll, bookkeeping, tax software, and vendor forms are consistent. If the company later changes its responsible party, address, or legal name, update the relevant IRS records instead of simply changing the name inside accounting software.
The useful mental model is simple: state formation creates the entity under state law; the EIN identifies its federal tax account; separate registrations activate the specific taxes, licenses, and accounts the business actually needs.