What a Federal Tax ID Number Is and Why You Need One

A Federal Tax ID Number Is Your Business's Social Security Number

A Federal Tax ID Number, also called an Employer Identification Number (EIN), is a nine-digit identifier the IRS assigns to businesses, nonprofits, trusts, and certain other entities. It works like a Social Security number, but for your business instead of you as a person. The IRS uses it to track tax filings, payroll withholding, and business accounts.

You need an EIN if you operate as a sole proprietor with employees, run a partnership or corporation, own a nonprofit, or file certain tax forms. Even if you work alone and have no employees, you may still need one depending on your business structure. The number stays with your business for life, even if you sell it or change locations.

Key Takeaways

An EIN is a nine-digit number issued by the IRS that identifies your business for tax purposes, separate from your personal Social Security number.
You must have an EIN if you have employees, operate as a corporation or partnership, or run a nonprofit organization.
Sole proprietors without employees can use their Social Security number for taxes, but many choose to get an EIN anyway for privacy and business separation.
You can request an EIN online through the IRS website for free, and you receive it when ready in most cases.
Banks, vendors, and contractors often ask for your EIN before opening accounts or issuing tax documents like 1099s.

When You Must Have an EIN

The IRS requires an EIN in specific situations. If you have employees—even one part-time worker—you must have an EIN to report payroll taxes and file Form 941 (Employer's Quarterly Federal Tax Return). If you operate as a corporation or partnership, an EIN is mandatory. Nonprofits, trusts, and estates also need one.

If you are a sole proprietor with no employees, you can use your Social Security number on your tax return instead. However, many sole proprietors get an EIN anyway because it separates their personal finances from their business finances, protects their Social Security number from being shared with vendors and contractors, and makes it easier to hire employees later without reapplying.

Certain business structures require an EIN regardless of size. If you operate as an LLC (limited liability company), S-corporation, or C-corporation, you need one. If you file Form 1065 (partnership return), Form 1120 (corporate return), or Form 990 (nonprofit return), an EIN is required.

How the IRS Assigns and Uses Your EIN

The IRS assigns EINs in a specific format: two digits, then a hyphen, then seven digits (for example, 12-3456789). Each number is unique to one business entity. The IRS uses your EIN to match tax returns you file, payroll documents your employees receive, and 1099 forms contractors send to you.

When you hire employees, you report their wages and withholdings using your EIN on Form 941. When a contractor does work for you and receives more than $600, they report it on a Form 1099-NEC, which they file with the IRS using your EIN. Banks and credit card processors report interest and payment information to the IRS under your EIN. This creates a paper trail the IRS uses to verify that your business income matches what you report on your tax return.

Your EIN is public information. Anyone can look up a nonprofit's EIN and see its Form 990 filing through the IRS Tax Exempt Organization Search. For private businesses, the EIN itself is not secret, but it is not widely published either. Still, you should protect it the way you protect your Social Security number to prevent identity theft or fraud.

How to Request an EIN From the IRS

You can request an EIN online, by mail, by fax, or by phone. The online method is fastest and free. Go to the IRS website (irs.gov), find the EIN process page, and complete Form SS-4 online. You will answer questions about your business structure, location, and the type of work you do. The IRS issues your number when ready after you submit the form, and you can print a confirmation letter right away.

If you explore by mail, send Form SS-4 to the IRS address listed on the form for your state. Processing takes about four weeks. By fax, you send the same form and typically receive your EIN within four business days. By phone, you call the IRS Business and Specialty Tax Line and speak to a representative who walks you through the form. Phone lines are busiest in January and February.

You do not need to pay a fee for an EIN. The IRS does not charge for issuing one, and no legitimate third-party service should charge you either. Some websites offer to "help" you get an EIN for a fee, but you can do it yourself for free in minutes.

What Information You Need to explore

Before you explore, gather basic information about your business. You will need your legal business name, the address where your business operates, your business structure (sole proprietor, partnership, corporation, LLC, nonprofit, etc.), and the type of business activity (retail, consulting, manufacturing, etc.). You will also need your personal Social Security number or ITIN (Individual Taxpayer Identification Number).

If your business has a responsible party—someone who owns or controls it—you will need that person's name, address, and Social Security number or ITIN. For partnerships and corporations, you may need the names and addresses of all owners or officers, depending on the structure. If you are explore on behalf of a nonprofit, you will need the organization's formation documents or a letter from the board.

Have your expected start date ready. This is the date you plan to begin business operations or the date you officially formed your entity. The IRS uses this to determine which tax year your first return covers.

EIN vs. Social Security Number for Business Taxes

As a sole proprietor without employees, you can file your business taxes using your Social Security number instead of an EIN. You report business income on Schedule C (Profit or Loss From Business) and attach it to your personal Form 1040. The IRS treats your business as an extension of you, not as a separate entity.

Using your Social Security number has downsides. Every vendor, contractor, and bank you work with receives your Social Security number on tax documents. This increases the risk of identity theft. It also makes it harder to separate your personal and business finances, which can complicate bookkeeping and make audits messier. If you later hire employees or change your business structure, you will need to get an EIN anyway.

Using an EIN instead keeps your Social Security number private and creates a clear boundary between your personal and business finances. Many banks will not open a business account without an EIN, even for sole proprietors. If you plan to grow your business or hire help in the future, getting an EIN early saves time.

What Happens After You Receive Your EIN

Once you have your EIN, use it on all business tax forms, payroll documents, and bank accounts. When you open a business bank account, the bank will ask for your EIN. When you hire employees, you provide your EIN to them so they can report it on their W-4 forms. When you file your business tax return, your EIN goes on the return itself.

Keep your EIN confirmation letter in a safe place. You may need to show it to banks, the IRS, or state tax agencies. If you lose it, you can request a new confirmation letter from the IRS or straightforward look up your EIN through the IRS Business Services Online tool if you have a username and password set up.

Your EIN does not expire. Even if your business closes, the number remains inactive in the IRS system. If you start a new business later, you will need a new EIN because each business entity gets its own number. You cannot reuse an old EIN for a different business.

Frequently Asked Questions

Do I need an EIN if I am a sole proprietor with no employees?

No, you can use your Social Security number instead. However, many sole proprietors get an EIN anyway to keep their Social Security number private and to separate personal and business finances. Banks often require an EIN to open a business account, even for sole proprietors.

How long does it take to get an EIN?

Online applications are processed when ready, and you receive your number right away. Mail applications take about four weeks. Fax applications typically take four business days. Phone applications are processed during the call if you reach a representative.

Can I change my EIN if I do not like the number?

No. The IRS assigns EINs randomly, and you cannot request a specific number or change the one you receive. Your EIN is permanent for that business entity.

What if I explore for an EIN but never start my business?

The EIN remains active in the IRS system. If you never use it, you do not need to do anything. The IRS will not penalize you for having an unused EIN. However, if you later use that EIN for a different business, the IRS may flag it as a discrepancy.

Do I need a separate EIN for each business I own?

Yes. Each separate business entity needs its own EIN. If you own two unrelated businesses, you need two EINs. If you own multiple locations of the same business under one legal entity, you use one EIN for all locations.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.