Whether you’re establishing a new business in the US, managing payroll, or filing tax documents, you’ve likely encountered the terms employer identification number (EIN) and taxpayer identification number (TIN). These terms are interrelated but have distinct applications. Understanding these distinctions is important for managing your business’s finances, legal standing, and tax obligations.

Below, we explain what EINs and TINs are, when to use them and common mistakes that can lead to delays or compliance issues.

What's in this article?

• Are TIN and EIN the same?
  
• How are EIN, SSN, and ITIN related to TIN?
  
• When should businesses use an EIN vs. another TIN?
  
• How to apply for an EIN
  
• How to obtain other types of TINs
  
• What happens if you use the wrong TIN?
  
• How to correct errors in EIN or TIN applications
  
• How Stripe Atlas can help
  

Are TIN and EIN the same?

TINs and EINs are not the same. An EIN (employer identification number) is a type of TIN (taxpayer identification number), but not all TINs are EINs. A TIN is a broad umbrella term used by the IRS to refer to any number used to identify a taxpayer—this includes EINs, Social Security numbers (SSNs), individual taxpayer identification numbers (ITINs), and others.

An EIN, sometimes called a federal tax ID, is specifically assigned to businesses, nonprofits, estates, and other entities for tax reporting purposes. So while every EIN is a TIN, the reverse is not true—an SSN, for example, is also a TIN but is issued to individuals, not businesses.

What is a taxpayer identification number (TIN)?

A TIN is a broad term encompassing several types of identification numbers the IRS uses to track individuals and entities for tax purposes. Any number officially issued by the IRS or Social Security Administration to identify a taxpayer qualifies as a TIN, such as SSNs, EINs, ITINs, and adoption taxpayer identification numbers (ATINs). An SSN is a type of TIN, issued to US citizens and eligible residents for individual tax reporting.

TINs and EINs are not interchangeable. An EIN is a specific type of TIN assigned to businesses and other entities, while a TIN is the overarching category that contains it. An EIN is always a TIN, but a TIN is not always an EIN.

What is an employee identification number (EIN)?

An EIN is a unique, nine-digit number assigned by the US Internal Revenue Service (IRS) to businesses, trusts, estates, and other entities for tax purposes. It is a specific type of TIN. Its primary use is to identify employers who have employees, but it’s also required for other entities such as partnerships, corporations, and nonprofits. Think of it as a Social Security number for businesses—it’s how the IRS tracks a business’s tax obligations. Businesses also use an EIN to manage payroll for employees and handle other business-specific tax matters.

How are EIN, SSN, and ITIN related to TIN?

EINs, SSNs, and ITINs are different types of TINs the IRS issues to track tax obligations. Here’s how they’re related:

EIN

EINs are for businesses and entities rather than individuals. The IRS issues them to businesses, organizations, trusts, and estates for tax identification purposes. They’re required for any business that has employees, operates as a corporation or partnership, or files employment, excise, or alcohol, tobacco, and firearms tax returns.

SSN

SSNs are the most common type of TIN for individuals. The IRS assigns them to US citizens and certain eligible residents, usually to track Social Security benefits. They also function as TINs for individual tax filings.

ITIN

ITINs are for individuals who cannot obtain SSNs. The IRS issues them to individuals who are required to pay taxes but aren’t eligible for SSNs. These include certain non-US residents, all non-US non-residents, and their dependents.

When should businesses use an EIN vs. another TIN?

Whether to use an EIN or a different type of TIN depends on your specific tax situation. Your business is legally required to have an EIN if:

• You have employees

• You operate as a partnership or corporation

• Your business files employment, excise, or certain other tax returns (e.g., alcohol, firearms)

• You’re a nonprofit or trust

When should a business apply for an EIN?

If your business is required to have an EIN, you should apply for one before you hire your first employee, open a business bank account, or file your first business tax return—whichever comes first. You can use an EIN to open business bank accounts, apply for business loans, and file business taxes, including payroll taxes.

Do LLCs need an EIN?

It depends on how your LLC is structured. Single-member LLCs with no employees are not required to have an EIN—you can use your SSN for tax purposes. However, multimember LLCs are treated as partnerships by the IRS and must have an EIN. Even if it's not required, many single-member LLC owners choose to obtain an EIN to keep business and personal finances separate and to avoid sharing their SSN with clients or vendors.

Do freelancers need an EIN?

Freelancers and sole proprietors are generally not required to have an EIN—your SSN typically suffices for filing taxes and completing W-9 forms for clients. But obtaining an EIN is often a smart move. It protects your personal SSN and makes it easier to open a dedicated business bank account. You'll also need one if you hire subcontractors or plan to form an LLC or corporation down the line.

As an individual, you need to use your TIN to file personal taxes. This is your SSN, if you have one, or your ITIN, if you’re a non-US resident or non-resident who isn’t eligible for an SSN.

How to apply for an EIN

There are several ways to apply for an EIN:

• IRS EIN Assistant (fastest): Apply online via the EIN Assistant on the IRS website and receive your EIN immediately. Available only if your principal business is located in the US or its territories.

• Mail: Complete and mail Form SS-4 to the IRS. Processing can take up to four weeks.

• Fax: Fax your completed Form SS-4 for faster processing—typically up to four working days.

• Phone (international applicants): Call the IRS international line if your business is located outside the US or its territories.

How to obtain other types of TINs

If you need an SSN, apply through the Social Security Administration (SSA) by filling out Form SS-5. You can submit the application in person at your local SSA office or by mail. You need to provide documentation proving your identity, age, and US citizenship or lawful immigration status.

If you need an ITIN, download Form W-7 from the IRS website. You can submit the application by mail to the listed IRS address or in person to an IRS-authorized certifying acceptance agent or IRS Taxpayer Assistance Center. You need to provide supporting documents—such as a passport or other government-issued ID—that prove your foreign status and identity. Processing ITIN applications typically takes seven weeks. Afterward, you receive your ITIN by mail.

What happens if you use the wrong TIN?

Using the wrong number – whether it’s an EIN, SSN, or ITIN – can cause several issues. Filing taxes with the wrong TIN can lead to rejected tax filings, delayed tax refunds, or fines from the IRS. If you file taxes with someone else’s TIN, the IRS might log your tax filing as missing and issue a late fee. This can create confusion with IRS records, and you might not be credited for the taxes you’ve already paid. Your income could be tied to someone else’s TIN, which creates issues for you and the entity whose TIN you’ve used.

Repeated errors with TINs can increase IRS scrutiny and the risk of an audit. When you file business documents – such as contracts and payroll filings – using the wrong TIN puts you at risk of non-compliance with tax laws and state regulations. This can even cause a breach of contract (e.g., if you were required to list an EIN on the contract but accidentally listed your personal TIN instead).

How to correct errors in EIN or TIN applications

If you’ve realised there’s an error in your EIN or TIN application, it’s important to correct it as soon as possible to avoid bigger problems later.

Here’s how to fix errors for each type of TIN:

Correcting an EIN application

• Call the IRS: If you notice a mistake after applying for an EIN, call the IRS Business and Specialty Tax Line at (800) 829-4933. Explain the error, and the IRS might be able to fix it quickly over the phone.

• Send a correction letter: If you can’t fix it over the phone, write a letter to the IRS. Send the letter to the appropriate IRS office, according to where your business operates. It can take a few weeks for the IRS to process your correction. In the letter, include:

  • Your business name, as it appears on the EIN application
    
  • Your TIN, if applicable
    
  • Your contact information
    
  • The mistake that needs to be corrected
    

• Update incorrect business details: If you’ve applied for an EIN and need to update information—such as your business name or address—file Form 8822-B to correct these details.

Correcting a TIN application

SSN application

• Contact the SSA: If there’s an error with your SSN application, you need to contact the SSA directly. You might need to fill out Form SS-5 to update or correct your information. When correcting an SSN error, be prepared to provide documents that prove your identity, such as a passport or birth certificate.
  

ITIN application

• Submit a corrected Form W-7: If your ITIN application has errors, you need to complete a new Form W-7 with the correct information. Include the required documents to verify your identity, such as your passport or other government-issued ID. Mail the updated Form W-7 and supporting documents to the IRS here:
  

Internal Revenue Service
ITIN Operation
P.O. Box 149342
Austin, TX 78714-9342

• Request a reissue: If your ITIN contains a mistake, such as an incorrect name or date of birth, you also need to submit an updated Form W-7. The IRS will issue a corrected ITIN after this form is processed.
  

How Stripe Atlas can help

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Join 75K+ companies incorporated using Atlas, including startups backed by top investors like Y Combinator, a16z and General Catalyst.

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Applying to form a company with Atlas takes less than 10 minutes. You'll choose your company structure, instantly confirm whether your company name is available and add up to four co-founders. You'll also decide how to split equity, reserve a pool of equity for future investors and employees, appoint officers and then e-sign all your documents. Any co-founders will receive emails inviting them to e-sign their documents, too.

Accepting payments and banking before your EIN arrives

After forming your company, Atlas files for your EIN. Founders with a US Social Security number, address and mobile phone number are eligible for IRS expedited processing, while others will receive standard processing, which can take a little longer. Additionally, Atlas enables pre-EIN payments and banking, so you can start accepting payments and making transactions before your EIN arrives.

A free year of Stripe Payments, plus $50K in partner credits and discounts

Atlas collaborates with top-tier partners to give founders exclusive discounts and credits. These include discounts on essential tools for engineering, tax, finance, compliance and operations from industry leaders like AWS, Carta and Perplexity. We also provide you with your required Delaware registered agent for free in your first year. Plus, as an Atlas user, you'll access additional Stripe benefits, including up to a year of free payment processing for up to $100K in payments volume.

Learn more about how Atlas can help you set up your new business quickly and easily and get started today.