An EIN (employer identification number, also called a federal employer identification number or FEIN) is a federal tax ID number for businesses, tax-exempt organizations and other entities, issued by the IRS, according to the IRS EIN page. Under the Form SS-4 instructions, it’s a 9-digit number, written like 12-3456789, and it does for your business roughly what your Social Security number does for you.
You need one if you have employees, pay employment or excise taxes, or operate a partnership, LLC or corporation, the IRS says. Under the single-member LLC rules, a single-member LLC with no employees and no excise tax liability doesn’t need one for federal tax purposes, though the IRS expects most new single-member LLCs to get one.
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Do you need an EIN? Which tax ID to use
| Your situation | ID you use | EIN required? |
| Sole proprietor, no employees | Your SSN (or ITIN) | No, unless you have a qualified retirement plan, must file employment, excise or alcohol, tobacco and firearms returns, or pay gambling winnings. Optional for banking or state tax. |
| Single-member LLC, no employees | Owner’s SSN or EIN for income tax | No, unless it has an excise tax liability. Needed anyway if your bank asks for one or state tax law requires one. |
| Single-member LLC with employees | The LLC’s own EIN for employment taxes | Yes |
| Multi-member LLC or partnership | EIN | Yes |
| Corporation | EIN | Yes |
| Owner with no SSN | ITIN for your own federal taxes; the business follows the rows above | Depends on the business, not the owner. You can list an ITIN as the responsible party on the EIN application. No SSN or ITIN? See our guide to federal and state tax IDs. |
Sources: IRS EIN page; Form SS-4 instructions, line 9a; IRS single-member LLC page; IRS ITIN page; IRS Get an EIN page.
The IRS checklist. Per the IRS EIN page, you need an EIN if you:
- Have employees
- Will need to pay employment, excise, or alcohol, tobacco and firearms taxes
- Withhold taxes on income, other than wages, paid to a non-resident alien
- Operate a partnership, LLC, corporation, tax-exempt organization, estate, trust (with some exceptions), retirement plan or IRA, real estate mortgage investment conduit or farmers’ cooperative
If none of these applies, you can still request an EIN for banking or state tax purposes, the IRS says.
EIN vs tax ID: how it compares to an SSN and ITIN
All three are taxpayer identification numbers (TINs), the umbrella term for numbers the IRS uses in the administration of tax laws. The Social Security Administration issues SSNs; the IRS issues all other TINs, including EINs and ITINs. So “tax ID” and “EIN” aren’t quite synonyms: an EIN is one kind of tax ID, the one for businesses.
| EIN | SSN | ITIN | |
| Issued by | IRS | Social Security Administration | IRS |
| Identifies | A business or other entity | An individual | An individual not eligible for an SSN |
| Used for | Business tax filing and reporting | Personal taxes and identity | Federal tax purposes only |
| Who sees it | Clients, banks and agencies you do business with | Keep private; give only where required | The IRS and those you file with |
Under the Form SS-4 instructions, an EIN is for use in connection with your business activities only, and the IRS says not to use it in place of your SSN or ITIN on your personal filings.
An ITIN is a 9-digit number for people who have a federal tax purpose and aren’t eligible for an SSN, the IRS says. It doesn’t authorize you to work in the U.S., doesn’t provide or change immigration status, and doesn’t serve as identification outside the federal tax system.
You apply for one on Form W-7. An ITIN covers you personally; whether your business needs an EIN still depends on the table above.
Single-member LLCs: the case that confuses people
For income tax, an LLC with one member is treated as an entity disregarded as separate from its owner, under the IRS single-member LLC rules. If it has no employees and no excise tax liability, it doesn’t need an EIN and uses the owner’s name and TIN for federal tax purposes. Even so, the IRS says most new single-member LLCs classified as disregarded entities will need to obtain one.
That changes the moment you hire. The LLC must then use its own name and EIN to report and pay employment taxes, the IRS says, even though its income still flows to your personal return. It may also need an EIN to open a bank account, or if state tax law requires one.
One detail trips people up: when a client sends a disregarded LLC a Form W-9, the W-9 should give the owner’s SSN or EIN, not the LLC’s EIN, per the IRS single-member LLC page. If you’re not sure which number goes where, ask your tax professional before you send it.
New to LLCs? Start with what an LLC is.
Not hiring yet: should you get one anyway?
Often, yes, for practical reasons rather than legal ones. Per the IRS EIN page, you can request an EIN for banking or state tax purposes even when federal tax rules don’t require one.
An EIN also gives you a business number to use on paperwork instead of your SSN (though, under the single-member LLC rules, a disregarded LLC’s W-9 still takes the owner’s number, as above). The EIN identifies your business to the IRS, so keep it as carefully as you’d keep your SSN.
If you’re a sole proprietor, the Form SS-4 instructions say one EIN generally covers you, however many businesses or trade names you run.
What most people should do: if you’ve formed an LLC or corporation, or plan to hire or open a business bank account, get one.
After you have an EIN
Name, address or responsible-party change. You don’t need a new EIN to change your business name, address or responsible party, the IRS says. The responsible party is the person in charge of the entity and its assets, named on the application.
Ownership or structure change. Per the IRS EIN page, you need a new EIN, in general, when you change your entity’s ownership or structure. For example, if a sole proprietorship incorporates or enters into a partnership, a new EIN is required, according to the Form SS-4 instructions.
Closing the business. An EIN isn’t something you cancel. The IRS can’t cancel an EIN, but it can deactivate it, per the IRS EIN page.
Lost your EIN. Check the notice the IRS sent when you applied, your business bank, any agency where you hold a state or local license, and past business tax returns, the IRS says. If you still can’t find it, call the IRS at 800-829-4933, Monday to Friday, 7 a.m. to 7 p.m. local time (Alaska and Hawaii use Pacific time). The IRS verifies your identity before giving you the number.
Mistakes to avoid when you apply
A name that doesn’t match your formation documents. Enter the legal name exactly as it appears on the charter or other applicable legal document, per the Form SS-4 instructions. For an LLC or corporation, that means forming with your state first: the IRS says entities should register with the state before applying.
Duplicate applications. EIN issuances are limited to one per responsible party, per day, by any method, under the Form SS-4 instructions. If you’re forming two entities with the same responsible party, plan for two days.
For the full application walkthrough, what to have ready, and state tax IDs, see our guide to federal and state tax IDs.
How MyCorporation helps
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Sources
- IRS, Employer identification number (page updated 17 Jul 2026). Definition, who needs an EIN, banking/state tax requests, name/address/responsible-party changes, ownership changes, deactivation, lost EIN and phone line. Verified 31 Oct 2026.
- IRS, Get an employer identification number (page updated 16 Oct 2026). SSN or ITIN for responsible party. Verified 31 Oct 2026.
- IRS, Instructions for Form SS-4 (Rev. 12/2025). Free of charge on IRS.gov for U.S. applicants (“you can apply for and receive an EIN free of charge on IRS.gov”); 9-digit format, business-use-only, one EIN per sole proprietor, new EIN on incorporation, line 1 legal name, line 9a sole proprietor (incl. gambling winnings), one EIN per responsible party per day. Verified 31 Oct 2026.
- IRS, Single member limited liability companies (page updated 27 Jul 2026). Disregarded entity, “most new single-member LLCs… will need to obtain an EIN”, the no-employees/no-excise exception, employment taxes, bank/state tax need, W-9. Verified 31 Oct 2026.
- IRS, Taxpayer identification numbers (TIN) (page updated 11 Jun 2026). TIN definition and types; SSA issues SSNs, IRS issues other TINs. Verified 31 Oct 2026.
- IRS, Individual taxpayer identification number (ITIN) (page updated 28 Oct 2026). 9 digits, eligibility, limits, Form W-7. Verified 31 Oct 2026.