When expanding your UK business into the US, one of the first steps you’ll need to take is getting an Employer Identification Number (EIN). The application process is designed for US businesses, so international founders might have a more difficult time with it, specifically when deciding which fields to leave blank, how to apply without a US address, and why a UK business might need an EIN.

Below, we’ll explain why and when UK businesses might need a US EIN, how they can apply for one, and what happens once they have one.

What’s in this article?

• What is an EIN, and why do UK businesses need one?
  
• Can a UK business get an EIN without a US presence?
  
• How can UK businesses apply for an EIN?
  
• What happens once you receive your EIN?
  

What is an EIN, and why do UK businesses need one?

A US EIN is a federal tax ID issued by the IRS. An EIN is similar to the UK’s Unique Taxpayer Reference (UTR). It’s how the IRS tracks your business’s activity in the US tax system.

You’ll use an EIN to file tax documents, hire US employees, open US business bank accounts, apply for licenses, and more. The number is not private, like a password, but it is still sensitive because banks and payment platforms use it to verify your business identity. Once issued, your EIN is yours for as long as your business exists (unless the structure changes substantially).

If you’re doing business in the US, you probably need an EIN. Here are some activities that require UK businesses to apply for one:

• Hiring US employees: If you’re paying employees in the US, you’ll need an EIN to report wages, file payroll tax documents, and issue forms such as W-2s. Even if your business is fully UK-based, the IRS requires a US tax ID when you have a US workforce.

• Opening a US business bank account: Most US banks won’t let you open a business account without an EIN. The bank uses the number for compliance and tax reporting. You also need one to apply for a business credit card or line of credit in the US.

• Using US-based platforms: Many US payment processors and platforms ask for an EIN during onboarding to verify your business. If you’re setting up a US Stripe account, for example, you’ll need an EIN.

• Filing tax forms or treaty claims: Even if you don’t owe US taxes, you might need to submit forms that require an EIN—for example, if you’re claiming treaty benefits or reporting US-sourced income. If you’ve set up a US branch or subsidiary, you’ll need an EIN to file corporate tax returns.

• Registering for US state taxes: If you’re selling goods or services in the US, you might need to register for state-level taxes such as sales tax or franchise tax. You’ll need an EIN to register with state tax authorities—even if you’re a remote seller with no US presence.

• Applying for licenses or permits: Many US business registrations and licenses—federal and local—require an EIN as part of the paperwork.

Can a UK business get an EIN without a US presence?

You don’t need a US address, bank account, or incorporated entity in the US to get an EIN. You also don’t need a US intermediary or address service to apply. The IRS lets non-US businesses, including UK businesses, apply directly.

The main difference for non-US businesses is the IRS’s online EIN application system isn’t available to international applicants. It’s restricted to entities with a principal office in the US or a US territory, and it expects the “responsible party” to have a US Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN).

As a UK business, you’ll have to apply via phone, fax, or mail. These methods aren’t as fast as the domestic online portal, but there’s a dedicated team, the EIN International Operation, that handles requests such as these.

If your UK business is planning any activity in the US that triggers the need for an EIN, such as opening a US bank account or hiring US-based staff, you should apply for an EIN right away.

How can UK businesses apply for an EIN?

The core of the process is simple: fill out Form SS-4 and submit it to the IRS. Here’s what that entails for international applicants:

Step 1: Gather your information

Before you get started, make sure you have all your information accessible. Be prepared to list:

• Your UK business’s legal name (as officially registered). If you use a separate trading name in the US, you can list that as a “trade name.” The EIN will be issued under your legal name.

• Your registered business address. You can use your UK address; there’s no requirement to have a US mailing address.

• A short explanation of why you’re completing the application. For example, “Compliance with IRS regulations” or “To hire US employees.”

• Your expected number of employees if you plan to hire US-based employees in the next 12 months. It’s fine to put “0” if you’re not planning to hire yet.

• The date you first expect to pay wages in the US. Fill this out only if you plan to hire US employees.

• A name and phone number the IRS can call if the agency has questions about the application.

• A third-party designee if you’re authorizing someone else to answer questions on your behalf, such as a legal advisor.

Step 2: Fill out Form SS-4

This is the official IRS form to apply for an EIN. It’s one page and free to download from the IRS website. You can fill it out online or print it and fill it out by hand.

As a UK business, be sure to follow the IRS’s international instructions:

• Include your responsible party’s full name. Leave the SSN/ITIN field blank, or write “Foreign” if they don’t have a US tax ID.

• Enter your UK mailing address—this is where your EIN confirmation will be sent.

There’s no fee to apply. Be cautious of services that try to charge you for submitting your application.

Step 3: Submit the form to the IRS

As an international applicant, you can send Form SS-4 by phone, fax, or mail.

Option 1: Apply by phone

Call the IRS International EIN line: +1 267 941 1099. This line is available Monday through Friday, 6:00 a.m. to 11:00 p.m. Eastern time. An IRS agent will ask you to read out the information from Form SS-4.

The person calling must be authorized to receive the EIN; they are typically the responsible party or someone designated on the form. If everything checks out, the IRS will issue your EIN during the call.

This is the fastest method for obtaining your EIN. You’ll receive the number on the spot, and the IRS will follow up by mail with a formal confirmation letter.

Option 2: Apply by fax

Fax your completed Form SS-4 to the IRS International Office: +1 304 707 9471. Include a return fax number (or email address) where the IRS can send your EIN confirmation.

Most faxed applications are processed in about four business days. If you don’t provide a return number, the IRS will mail your confirmation instead, which takes longer.

You can use a physical fax machine or an online fax service. Make sure your form is signed and legible. If you fax from the UK, double-check that the transmission was successful.

Option 3: Apply by mail

Mail the completed and signed Form SS-4 to:

Internal Revenue Service
Attn: EIN International Operation
Cincinnati, OH 45999
USA

Regular post is fine, but tracked delivery can give you peace of mind. Expect to receive your EIN in about four weeks. This method is reliable but not recommended if you’re working on a deadline.

What to do if your application is delayed

If you don’t receive your EIN in the expected time frame or if you’re concerned your fax or mail submission was lost or mishandled, you can call the IRS to follow up. Delays often stem from one of three issues:

• Incomplete or mismatched information on the form

• Missing return contact information

• Time zone or call volume challenges if applying by phone

No matter which way you apply, double-check everything on the form before sending it. If there is a mistake, the IRS might follow up by phone or mail. If you apply by phone, it’s easier to make real-time corrections.

What happens once you receive your EIN?

You can use your EIN immediately, even if the confirmation letter—called a CP 575 letter—hasn’t arrived yet. Once it arrives, keep the CP 575 letter in a safe place. You might need it for bank compliance, platform onboarding, or proof of US tax registration.

Your EIN stays with your business indefinitely. It doesn’t expire, and you don’t need to renew it. You are responsible for updating the IRS if your business name, address, or responsible party changes.

Getting an EIN doesn’t automatically trigger US tax obligations; it just means the IRS has a file open on your business. If your business starts generating US-source income, hires employees in the US, or creates a taxable presence, then tax filings might follow. But simply holding an EIN doesn’t create a liability.