Employer Identification Number

Running a business by yourself can be overwhelming, especially as it scales. Building a team can significantly ease your workload and support business growth. With the right pieces in place, your business isn't solely dependent on you, and you can pursue more projects and opportunities than when you started. As you interview prospective team members, don't forget your employer identification number (EIN), a key element of federal tax compliance.

Small business owners forming a corporation, partnership, or multi-member limited liability company (LLC), as well as sole proprietors and single-member LLC owners deciding whether they need one, should use this guide to understand what an EIN is, which entities need it, how to apply, when a business needs a new one, and what it's used for day-to-day.

What is an EIN?

Obtaining your EIN is an essential part of running your small business. The EIN is a nine-digit number unique to your business, no matter what state you're in or where you’re located. You register for an EIN with the IRS, which will assign a number to your company for free.

While multiple businesses may have similar names, no two businesses share an EIN. You’ll be using this number often for handling wages and taxes and submitting other paperwork to the government. While your EIN will be the primary identifier for your company with the federal authorities, you may need separate state tax ID numbers for your state-level obligations.

EIN vs. SSN vs. ITIN

While EINs, SSNs, and ITINs can sometimes be used interchangeably, they are distinct. An SSN identifies an individual, an ITIN identifies an individual who isn't eligible for an SSN but has federal tax obligations, and an EIN identifies a business entity.

A sole proprietor who hasn't obtained an EIN can use their SSN in its place on formal business tax filings.

Which Business Entities Need an EIN?

Any business in the United States or the U. S. territories can apply for an EIN, but the specific need depends on the type of business entity. Most businesses need an EIN, whether or not they intend to hire employees.

Sole Proprietorships

Sole proprietorships usually won’t need an EIN, as the owner can use their Social Security number instead. The business is not a separate legal entity from the individual in a sole proprietorship, so the IRS doesn’t require a unique nine-digit number other than the SSN.

Corporations

Any corporation must apply for an EIN, even if it won’t have any employees. Corporations are distinct legal entities separate from their owners and stockholders, and the EIN allows the IRS to identify them directly.

S Corporations

S corporations are corporations that have filed for a special tax status with the IRS, whereas regular corporations are known as C corporations. This status allows the corporation’s owners to report their income as personal income instead of paying taxes at the corporate tax rate first. This avoids a C corp's double taxation. S corporations must also apply for an EIN.

Multi-member LLCs

LLC business entities typically only need an EIN if they have multiple members. Single-member LLCs with no employees don't need an EIN because the IRS can treat them as a sole proprietorship.

Multi-member LLCs will need an EIN. If you file, you will also need an EIN to have your LLC taxed as a C corporation or S corporation.

Partnerships

Partnerships, another common small business entity with multiple partners, also require owners to register their business for an EIN.

Other Situations That Require an EIN

While hiring employees is commonly cited as a top reason to obtain an EIN, other scenarios also require one.

• Filing employment, excise, or alcohol/tobacco/firearms tax returns

• Withholding tax on income (other than wages) paid to a nonresident alien

• Administering a Keogh plan, trust, estate, or non-profit organization

How to Apply for an EIN?

You can obtain an EIN directly from the IRS for free, with a few options to choose from. Your choice of application method will determine how long it takes to receive your EIN.

Keep in mind that the IRS only registers one EIN per responsible party per day. This means that you can’t apply for multiple EINs simultaneously. This also means that, no matter how you apply for an EIN, you will need to prove who you are and that you are a legally responsible party for your business entity.

Who Is the “Responsible Party”

The responsible party is the individual who ultimately owns or controls your business, or who exercises ultimate effective control over it. The responsible party must possess a valid SSN, ITIN, or EIN of their own.

The one-EIN-per-day limit applies to the responsible party for your business.

Online

The most convenient and straightforward option is to apply for an EIN online. You'll need a valid ITIN or SSN to identify yourself as the responsible party for your business.

If you apply online, you must complete the application in one session. You will lose your progress if you encounter the 15-minute session timeout. IRS application hours are weekdays 6:00 a.m. to 1:00 a.m. ET; the following day, Saturday, 6:00 a.m. to 9:00 p.m. ET; Sunday, 6:00 p.m. to midnight ET. You'll receive an EIN immediately after your information is validated during the online session.

Don’t panic if you receive an error message and can't obtain your EIN at that time. This doesn’t necessarily mean anything is wrong with your application; it just means the online system can’t process it. If this happens, file IRS Form SS-4, Application for Employer Identification Number (EIN), by fax or mail instead.

Fax

If you had issues with the online application process, you can fax your completed Form SS-4 directly to the IRS.

If you apply using the fax machine method, you'll want to check online and make sure you use the appropriate and up-to-date fax number. If you also provide your own fax number, and you should, you'll receive a fax containing your new EIN within four business days.

Mail

You can also apply by mail. This process is slower, but it works perfectly well if you’re not in a hurry. Make sure your SS-4 form is complete, and mail it to the proper IRS office for processing. You should get your new EIN in the mail in four weeks or less.

Telephone

If you want to get your EIN processed quickly but don’t feel confident using the online method, you can also register by calling the IRS Business and Specialty Tax Line for telephone assistance.

Call 800-829-4933 on a weekday between 7:00 a.m. and 7:00 p.m., and an agent will complete the application for you over the phone. You should have your new EIN by the end of the conversation.

How Much Does an EIN Cost?

If you handle the process yourself, applying for an EIN is free. Reputable third parties can also obtain an EIN for you for a small fee. They handle the paperwork and ensure the application is accurate and error-free.

If you need an EIN quickly and would rather someone else handle the process, a third party may be the best option.

Why Is an EIN Important?

Your unique nine-digit EIN is necessary for several reasons. Beyond meeting legal requirements, it can help business owners operate more efficiently and pursue new opportunities.

Business Banking

You need an EIN to open a business bank account, which helps keep personal and business finances separate. Sole proprietors may open a business banking account using a Social Security number, but other entities typically need an EIN. The bank will likely ask for additional documentation as you apply.

Business Loans

An EIN also helps you establish business credit and apply for larger loans. When you apply for credit, your EIN will appear on your business credit report, and lenders will use it to find your business credit history.

Lenders often expect applicants to have a business bank account already, and they will check your business credit using your EIN before deciding whether to help with funding.

Business Taxes

You’ll definitely need your EIN as your federal tax identification number for your tax returns. If your business entity files a tax return as a separate legal entity, you'll need your EIN, and you might face financial penalties without one. The EIN is also important for withholding taxes on income long before you file the tax return.

If you run a non-profit entity eligible for tax-exempt status, you’ll need an EIN for that application as well, even though you won’t pay taxes through that business entity.

Hiring Employees

You'll also need an EIN if you plan to hire employees. Not every business needs employees beyond the owners, but if you plan to grow, you will eventually need help. Then you’ll need the EIN to handle their tax withholding and to set up payroll.

When Does a Business Need a New EIN?

In some cases, an existing business must apply for a new EIN even if it already has one. Scenarios include:

• Switching from a sole proprietorship to a corporation or partnership

• A corporation going through specific statutory changes

• Receiving a new charter from the state

• A business that's emerging from bankruptcy

Not every change demands a new EIN. Simply changing a business name or location generally does not require action on your part.

EIN and BOI Reporting

FinCEN BOI reporting, created under the Corporate Transparency Act, aimed to combat money laundering, terrorist financing, and tax fraud by identifying the actual people who own or control a business. The EIN application process was totally separate from BOI reporting.

Under the current FinCEN rule for 2026, most domestic small businesses no longer need to file BOI reports, while certain foreign reporting companies still do. While this reporting is no longer required, a future administration can revive it.

Getting Your Business's Tax ID Set Up the Right Way

For many small business owners, obtaining an EIN is essential, and now you have a better idea about what to do with it once you get yours. Make sure your business is structured properly as you move through the process. If you haven't formally structured your operations yet, or are considering a switch, expert guidance and support are critical.

Ensure your business is formed correctly with 1-800Accountant's full-service entity formation solution. Your goals, income, and long-term plans guide the process, ensuring your business is formed correctly from the start.

FAQs About Employer Identification Numbers

How long does it take to get an EIN?

The time it takes to get your EIN depends entirely on how you apply. If you apply online through the IRS website, the process is automated, and the IRS issues your number immediately. If you choose to submit Form SS-4 by fax, it takes about four business days, while applying by mail typically takes four weeks.

Can I get an EIN without a Social Security number?

Yes, you can obtain an EIN without having an SSN. You can't use the instant online application without an SSN or ITIN, but other options exist. You can complete IRS Form SS-4 and submit it via mail or fax, or international applicants can call the IRS directly to receive it.

Is an EIN the same thing as a tax ID number?

An EIN is a specific type of TIN, but they are not the same thing. A "tax ID number" is a broad umbrella term used by the IRS that includes SSNs, ITINs, and EINs. An EIN specifically refers to the nine-digit number assigned exclusively to businesses and organizations for corporate tax purposes.

Can I use one EIN for more than one business?

No, you cannot use a single EIN for multiple distinct legal business entities. The IRS requires every separate corporation, partnership, or LLC to have its own unique identification number. However, if you run multiple businesses as separate "Doing Business As" brands under one overarching sole proprietorship or parent company, they can share that single entity's EIN.

Do I need a new EIN if I change my business name or address?

No, changing your business name or physical address does not require a new EIN. You only need to report the updated details to the IRS using the appropriate official notification forms or when you file your annual tax return. You only need a new EIN if your fundamental business structure changes, such as converting from a sole proprietorship to a corporation or LLC.

What should I do if I lose or misplace my EIN?

If you misplace your EIN, first look for the original CP 575 confirmation letter the IRS issued when the account was created. You can also find the number on previously filed business tax returns, business bank statements, or business license applications. If you still cannot find it, you can call the IRS Business & Specialty Tax Line at 800-829-4933 to have an agent give you the number after you verify your identity.

Do I still need to file BOI after I get an EIN?

If your business is a domestic U. S. company, you no longer have to file a BOI report. As of a permanent final rule effective in August 2026, FinCEN.gov eliminated the BOI reporting requirement for all U. S. companies and U. S. persons. Only foreign-formed companies registered to do business in the U. S. are still subject to the 30-day reporting window after state registration.