Whether you’re launching a new business or seeking financing for an established one, at some point, you’ll likely run into a reference to or a request for your Form SS-4. Here’s what you need to know about this critical document.

What is Form SS-4?

IRS Form SS-4 is used to apply for an Employer Identification Number (EIN). Typically, when someone, such as a lender, requests your Form SS-4, they’re referring to the notice the IRS will send you in response to your application, not the actual application itself.

What is an EIN?

An EIN is a nine-digit number assigned for tax filing and reporting purposes to:

  • Employers
  • Sole proprietors
  • Corporations
  • Partnerships
  • Estates
  • Trusts
  • Certain individuals
  • Other entities.

It’s similar to a Social Security number but is formatted differently (12-3456789) and isn’t issued with a card. 

Why would my business need an EIN?

If you have employees, you need an EIN for payroll taxes. Businesses that operate as a corporation or a partnership (including limited liability companies) also need an EIN to file their income tax returns. Sole proprietorships and single-person LLCs without any employees are the only types of businesses exempt from that requirement. But all U.S.-based businesses have the option of obtaining an EIN.

Should I apply for an EIN if I’m not required to?

Even if you aren’t legally required to have an EIN, it’s a good idea to apply. For starters, you’ll need an EIN to open business banking and credit card accounts. And, just like a lending institution would request your Social Security number as part of the application process for a personal loan, business lenders will generally request your EIN.

Again, it’s the notice they want to see, not your application. Lenders can’t rely on a tax return because it might have a typo or error in the EIN. An IRS-issued notice doesn’t carry this risk.

Sole proprietorships and single-member LLCs without employees may be able to apply for a loan in the owner’s name, using a Social Security number instead of an EIN.

How do I file a Form SS-4?

You can submit it online through the IRS website, by mail, or via fax to the IRS service center in your state. International applicants must call (267) 941-1099; the online, mail, and fax options aren’t available.

What kind of information will I need to complete Form SS-4?

The current version of Form SS-4 is only a single page. To fill it out, you’ll need to know:

  • The legal name and address of your business
  • The business’s trade name, if different from the legal name
  • The name of the “responsible party” (that could be the business owner or the individual that controls, manages, or directs the applicant entity and the use of its funds and assets)
  • The responsible party’s Social Security number, EIN, or individual tax identification number
  • The entity type
  • Reason for applying (the form provides several options, including a fill-in-the-blank “Other”)
  • The date the business started or was acquired
  • The closing month of the accounting year (typically December)
  • The highest number of expected employees in the next 12 months
  • The first date wages were paid
  • The entity’s principal business activity (the form provides several options, including a fill-in-the-blank “Other”)
  • The entity’s principal line of product or service

If I have multiple businesses, do I need to file more than one Form SS-4?

It depends on your entity type. For example, if you’re a sole proprietor, you should file one form because you need only one EIN. That’s true regardless of the number of businesses you operate as a sole proprietor or the number of trade names under which you operate.

When a sole proprietor incorporates or enters a partnership, though, a new EIN is required (see below). And each corporation in an affiliated group must have its own EIN.

When will I receive the notice?

If you apply online, you’ll receive the notice as a PDF file immediately after filing. According to the IRS, it takes one to two weeks to receive a notice after faxing an application and at least four to five weeks after mailing the form.

What if I haven’t received my EIN by the time I need to file a tax return?

Don’t worry. The IRS says you can simply write in “Applied for” and the date you applied in the space included on the tax return for the EIN. Don’t provide your Social Security number in lieu of an EIN.

What if the information on my original Form SS-4 changes?

You’re obligated to keep your Form SS-4 information current. You can submit Form 8822-B to report changes to your responsible party, mailing address, or location. Changes to responsible parties must be reported to the IRS within 60 days.

What if I forget my EIN or misplace my notice?

You can call the IRS Business & Specialty Tax Line at (800) 829-4933— but they’ll need your EIN to search for a notice in their records. To locate the EIN, try:

  • Searching your computer for the PDF if you applied online
  • Contacting the bank if you used your EIN to open an account
  • Contacting the agency if you used your EIN to apply for a state or local license
  • Checking past tax returns 

When do I need to apply for a new EIN?

Generally, you’ll need a new EIN when your business’s ownership or structure has changed. Changing the name of your business alone doesn’t require a new EIN.

Certain business types must file for a new EIN in the following circumstances.

Sole proprietors that:

  • File for bankruptcy,
  • Incorporate,
  • Take on partners and operate as a partnership, or
  • Purchase or inherit an existing business that they operate as a sole proprietorship.

Corporations that:

  • Receive a new charter from the secretary of state,
  • Are a subsidiary of a corporation using the parent’s EIN or become a subsidiary of a corporation,
  • Change to a partnership or a sole proprietorship, or
  • Are created after a statutory merger.

Partnerships that:

  • Incorporate,
  • Are taken over by one of the partners and operated as a sole proprietorship, or
  • Result from ending an old partnership and re-starting as a new partnership.  

How can I cancel my EIN?

You can’t — an EIN is the permanent federal taxpayer identification number for the assignee entity. Even if you never use it to file tax returns, the EIN won’t be reused or reassigned.

If you determine that you don’t need an EIN after receiving one (for example, because the business never launched), you can only close your business account with the IRS. You’ll need to send a letter with the complete legal name of the entity, the EIN, the business address, and the reason you wish to close your account. If you have your notice, you should include that, too. Mail the letter to:

Internal Revenue Service
MS 6055
Kansas City, MO 64108


Internal Revenue Service
MS 6273
Ogden, UT 84201

What should I do if I suspect someone else is using my EIN for fraud?

Complete and submit Form 1403-B if you receive a:

  • Rejection notice for an electronically filed return because the IRS already has a return on file for that same period,
  • Notice about a tax return that you didn’t file,
  • Notice about Forms W-2 filed with the Social Security Administration that you didn’t file,
  • Notice of a balance due that you don’t owe, or
  • EIN notice when you never applied for an EIN (see below).

What should I do if I receive an EIN I didn’t apply for?

The IRS advises you to first check to see if someone legitimately acting on your behalf requested it — for example, your accountant, business partner or associate, or bank. Go ahead and file Form 1403-B, though, if you determine your identity has been misused and an EIN improperly assigned to you.

Barbara C. Neff has been writing about a variety of legal and other topics since 2001. She has a law degree and a master's degree in journalism.
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