Key Takeaways

  • A company tax number (also called an EIN or federal tax ID) is a unique nine-digit number assigned by the IRS to identify your LLC or business for tax, banking, and regulatory purposes.
  • You must have a company tax number if your LLC hires employees, files excise taxes, or has more than one member.
  • An EIN is required for opening business bank accounts, securing credit, paying payroll taxes, and working with vendors.
  • Your company tax number is not public, but you can share it with financial institutions, suppliers, and government agencies as required.
  • You can apply for an EIN online, by mail, fax, or phone, but only one person per day can apply for one on behalf of the business.

An LLC tax identification number is a nine-digit number  the IRS uses to distinguish your company from other business entities. 

Basics of LLC Tax IDs

If a limited liability company has even one employee, the IRS requires the company to have a tax ID number. Similarly, LLCs that have multiple members must have a tax ID.

Tax ID numbers are also commonly known as Employer Identification Numbers (EIN). Once you've been issued a tax ID number, the IRS will use the number to identify your company, much as the government uses Social Security Numbers to identify individual people.

Entities that are required to obtain tax ID numbers include:

A sole proprietor of an LLC that is interested in hiring an employee for the first time will need a tax ID number before they can make their hire. However, if an LLC has a sole proprietor and no employees, then the company owner can use his Social Security Number for tax filings instead of getting a tax ID number.

If you choose to use your Social Security Number instead of a tax ID when filling out forms for vendors and clients, you should be aware that you may be at risk for identity theft. Many people choose to acquire their tax ID themselves, although it's also possible to appoint someone to apply for the number on your behalf.

Acquiring a tax ID number is one of the many important steps to forming your LLC. If you complete these steps successfully, you will be able to enjoy the limited liability protections and versatile structure of this business entity. Hiring an attorney that understands the ins and outs of LLCs is a good decision if you want to successfully form your company. 

What a Company Tax Number Is Used For

A company tax number — formally known as an Employer Identification Number (EIN) — serves as the federal identifier for your business. It is to your LLC what a Social Security number is to an individual. Beyond federal tax filing, the EIN plays a crucial role in nearly every official interaction your business will have, including:

  • Filing business taxes: LLCs use the EIN to report income, pay payroll taxes, and file excise taxes.
  • Opening business bank accounts: Most banks require an EIN to verify your company’s legitimacy.
  • Hiring employees: Federal law requires businesses to have an EIN before hiring and paying workers.
  • Applying for business credit: Lenders often request an EIN when evaluating business creditworthiness.
  • Applying for licenses and permits: Many state and local agencies require a company tax number on applications.
  • Filing certain state taxes: Some states require an EIN for state tax filings, sales tax permits, or unemployment insurance accounts.

Even single-member LLCs may benefit from having a company tax number, as it adds a layer of privacy by limiting the need to use a personal Social Security number on official documents.

LLC Tax IDs for Banking

You will need your tax ID number to complete some of your LLC's most important banking tasks, including securing a line of credit, obtaining permits for your business, and establishing an LLC bank account. All of your LLC's banking and tax documents will need to include your tax identification number. Your bank can quickly identify your LLC by using your ID number.

Banks also want proof that your LLC and its members are legally separate, which is why they will request that you provide a copy of your Articles of Organization along with your EIN. A tax ID is required to open bank accounts for your business and to hire company employees. 

EIN and Privacy: What’s Public and What’s Not

Business owners are often concerned about whether their company tax number is publicly available. The IRS treats EIN information as confidential and does not publish or share company tax numbers in any public database. Only the “responsible party” — such as a company owner, officer, or managing member — can call the IRS to obtain or verify an EIN on file.

However, some business information may appear in public records, such as company names, registered agents, or state filings. These records do not include the EIN itself. When you share your EIN with vendors, clients, or lenders, it’s essential to store and transmit it securely to reduce the risk of identity theft or fraud.

If you misplace your company tax number, you can typically find it on past tax filings, official IRS correspondence, or by contacting the IRS Business & Specialty Tax Line.

EINs and Vendors

If you want to work with vendors, your LLC will need a tax ID, as many vendors avoid working with businesses that don't have these numbers. In addition, if you have plans to sell goods to them, you will need an ID number before you will be allowed to offer your items. Some vendors will allow you to make wholesale purchases if you have a tax ID number. 

Common Situations That Require a Company Tax Number

Beyond vendor relationships, there are many scenarios in which your business will be expected to provide its company tax number:

  • Business entity changes: If you restructure from a sole proprietorship to an LLC or corporation, you’ll need a new EIN.
  • Ownership changes: Acquiring or merging with another company often triggers a new EIN requirement.
  • Adding partners or members: A single-member LLC that adds partners must obtain a new company tax number.
  • Filing excise or alcohol/tobacco/firearms taxes: These specialized taxes require a valid EIN.
  • Withholding taxes for foreign employees: Any business employing non-U.S. citizens will need an EIN for tax compliance.

Understanding these trigger events can help ensure your LLC stays compliant and avoids delays in tax processing or regulatory filings.

How to Get a Tax ID

Visiting the IRS website is one of the ways to acquire a tax ID number. You can also obtain an EIN by phone at 800-829-4933. Depending on the time of day you visit the website, you may not be able to file an application, as it is only available during certain periods. Applying online is a quick and easy solution for obtaining a tax ID.

The online application that you will fill out is identical to IRS Form SS-4. You can review a copy of Form SS-4 before beginning your application so that you'll know what questions you'll need to answer and what information you should provide. LLCs that are located in the U.S. or its territories can apply for a tax ID online.

If you want a new tax ID, you should possess either a:

  • Social Security Number
  • ITIN
  • EIN

You can only apply for one EIN a day, and only one person from your LLC can fill out the application. You must complete the application in one session. The application will expire after being idle for fifteen minutes, after which you will need to start over. You should instantly receive your ID number after you have completed your online application. When filling out your application, you should indicate the structure of your business by checking the option for an LLC.

Applying for a Company Tax Number: Step-by-Step

The IRS offers multiple methods for obtaining a company tax number. The most common and fastest option is the online application process, but alternatives exist for businesses that prefer other methods or are located outside the U.S.:

  1. Online Application: Complete Form SS-4 on the IRS website. You must finish the application in one session, and the EIN is issued immediately upon completion.
  2. By Fax: Fill out Form SS-4 and fax it to the IRS. Approval typically takes four business days.
  3. By Mail: Mail a completed Form SS-4 to the IRS. Processing can take four to six weeks.
  4. By Phone (International Applicants): Non-U.S. entities can apply by calling the IRS at +1-267-941-1099.

Before applying, ensure you have the following information:

  • The legal name and address of your business
  • The name and SSN or ITIN of the responsible party
  • The business structure (e.g., LLC, partnership, corporation)
  • A brief description of your business activity

Remember, you can only apply for one EIN per day per responsible party. If you plan to register multiple businesses, stagger your applications accordingly.

Frequently Asked Questions

  1. What is a company tax number?
    A company tax number, or Employer Identification Number (EIN), is a unique nine-digit number issued by the IRS to identify your business for tax and regulatory purposes.
  2. Do all LLCs need a company tax number?
    Any LLC with employees, multiple members, or excise tax obligations must have an EIN. Even single-member LLCs often obtain one to separate business and personal finances.
  3. Is my company tax number public?
    No. The IRS does not make EIN information public. Only authorized parties, such as the business owner or officer, can request EIN verification.
  4. Can I change my company tax number?
    In some cases, such as restructuring your business or changing ownership, you may need to apply for a new EIN.
  5. How long does it take to get an EIN?
    If you apply online, you typically receive your EIN immediately. Fax applications take about four days, while mail applications may take up to six weeks.

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