US Tax ID Number: EIN, ITIN or SSN, Which One You Need

"Do you have a US tax ID number?" The question comes from US customers, platforms, banks and accountants, and it is less precise than it sounds. US law has no single tax number. It has several, issued by two different agencies, for different purposes and to different people. This article explains the three that almost always matter to you, the EIN, the ITIN and the SSN, shows which number goes on which form, and when the tax number from your home country in Europe replaces the US number.

1What "US tax ID number" actually means

The umbrella term is the Taxpayer Identification Number, or TIN. Under the regulations to § 6109 of the Internal Revenue Code there are several types: the Social Security Number, the Individual Taxpayer Identification Number, the Adoption Taxpayer Identification Number and the Employer Identification Number. The first three identify individuals; the EIN identifies employers and anyone who is not an individual, meaning corporations, partnerships, trusts and estates.

The SSN is issued by the Social Security Administration; all the other numbers come from the IRS. They look almost the same. SSNs and ITINs use the format 000-00-0000, and according to the IRS an ITIN always begins with a 9. The EIN uses the format 00-0000000. So when you read a number, the hyphen after the second digit tells you it belongs to an entity.

The forms determine when you need a number. According to the IRS, a TIN goes on tax returns, information returns and many certificates. On a form such as the W-8BEN it is required if you claim treaty benefits (except for income from publicly traded securities), if you claim income as effectively connected with a US trade or business, or if you claim an exemption for certain annuities.

2The EIN: your company's number

The EIN is a business's federal tax number. According to the IRS, every partnership, LLC and corporation needs one, as does anyone who has employees or withholds tax on payments to nonresident aliens. A single-member LLC needs its EIN for, among other things, the pro forma 1120 with Form 5472; a multi-member LLC needs it for Form 1065. Which return your LLC files is covered in our article on the US LLC tax return.

The IRS charges nothing for the number, and it explicitly warns against websites that charge a fee for an EIN. There are four ways to apply. Online only works if the company was formed in the US, has its principal place of business in the US, and the responsible party has an SSN or ITIN. Without that number, you are left with fax or mail; the IRS quotes about four business days by fax and about four weeks by mail. If the principal place of business is outside the US, you can also apply by phone at 267-941-1099, Monday to Friday from 6 a.m. to 23 (11 p.m.) Eastern Time.

The application, Form SS-4, names the responsible party: the individual who ultimately owns or controls the company. If that person has neither an SSN nor an ITIN and cannot get one, they enter "foreign" or N/A on line 7b. According to the IRS, a nominee may not file the application. The IRS issues only one EIN per responsible party per day. Form the company with the state first and apply for the number afterwards; otherwise, the IRS says, the application may be delayed.

You can use the EIN right away, for example to open a bank account or get a business license. For e-filing a return and matching through the IRS TIN Matching program, the IRS allows up to two weeks. An EIN cannot be canceled; the IRS can only deactivate it. If the ownership structure or legal form changes, you generally need a new one; a new name, a new address or a new responsible party does not require one.

2.1An EIN just for the treaty

Even a foreign company with no US filing obligation may need an EIN, for example a European company that claims tax treaty benefits on its W-8BEN-E without giving a foreign tax number. The IRS describes a dedicated route for this: Form SS-4 carries a note such as "For W-8BEN Purposes Only", and the IRS records the company as having no filing requirement. If the IRS later writes to it about a return anyway, it should reply immediately that it is not required to file.

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3The ITIN: the tax number for people without an SSN

The ITIN is the number for individuals who have a tax purpose but cannot get an SSN. The regulations to § 6109 and the IRS website say the same. According to the IRS, you have a tax purpose if you must file a US federal tax return, claim a refund or tax benefit on a return, are claimed as a spouse or dependent for a benefit, or must provide a number for another tax reason. A return showing only zeros generally does not establish such a purpose, according to the IRS.

The ITIN is purely a tax number. It does not authorize you to work in the US, does not change your immigration status, gives no entitlement to Social Security benefits and does not serve as ID outside federal tax law.

3.1What the IRS requires for the application

You apply for an ITIN with Form W-7. On Form W-7 you check the reason you need the number; the instructions list reasons a through h, such as a nonresident alien's treaty claim or their own tax return. As a rule, Form W-7 is attached to the federal tax return you need the number for, meaning Form 1040 or Form 1040-NR; the number field stays blank and the IRS fills in the ITIN. For certain cases the instructions list exceptions to this rule, which require their own supporting documents.

On top of that, you need proof of your identity and foreign status. The IRS accepts thirteen documents. The passport is the only one that is sufficient on its own. At least one document must include a photo, and all must be current. The IRS requires originals or copies certified by the issuing agency; a simple notarized copy is generally not enough. According to the instructions, US embassies and consulates also offer certification.

You can submit by mail to the IRS ITIN office in Austin, in person at a Taxpayer Assistance Center with ITIN service in the US (by appointment), or through an Acceptance Agent. A Certifying Acceptance Agent, also available outside the US, can verify most documents and hand them straight back to you; originals sent by mail come back within 60 days, according to the IRS. The IRS says to expect word on your application within seven weeks, or nine to eleven weeks during peak season (January 15 to April 30) and for applications from abroad. The IRS confirms the assignment with notice CP565.

If you don't use your ITIN on a federal tax return for three consecutive tax years, it expires on December 31 of the third year. You then have to renew it before using it again. Read more in our articles Applying for an ITIN and Expired ITIN.

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4The SSN: the number that comes with work authorization

The Social Security Number is issued not by the IRS but by the Social Security Administration, on Form SS-5 and with proof of identity, age and citizenship or lawful status. Who is eligible is set out in 20 CFR 422,104: US citizens, green card holders and foreign nationals authorized to work in the US on another legal basis, for example with a work visa.

Without work authorization, the agency issues an SSN only for a valid non-work reason. The rule names two: a federal law requires the SSN for a federally funded benefit you are already entitled to, or a state law requires it for public assistance. Such a card is marked "NOT VALID FOR EMPLOYMENT". A tax return, a bank account or a business account are not among these reasons. If you only need a number for tax purposes, you get an ITIN.

ITIN and SSN are mutually exclusive. If you have an SSN or are eligible for one, you can't get an ITIN, and if you have an SSN application pending, only once the agency has denied it. If you get an SSN after your ITIN, for example with a work visa, you notify the IRS and use only the SSN from then on. Conversely, an SSN once issued remains your number for all tax purposes, even if you leave the US and become a nonresident alien.

5Which number for what

For entrepreneurs from Europe, two numbers almost always come together: the EIN for the US company and a personal number for the owner as soon as he or she has to file a US return. The single-member LLC with US business is the most common example. It needs the EIN for its pro forma 1120, and its owner needs an SSN or ITIN for Form 1040-NR, because for tax purposes the profit belongs to the owner. Our guide to forming a US LLC shows how to set up such a company without living in the USA.

Not every number you are asked for has to be a US number. A freelancer working for a US client usually needs no US number on the W-8BEN, as long as no treaty benefits are claimed. And even with a treaty claim, the forms often accept the tax number from your country of residence instead. Our filling guides for the W-8BEN and the W-8BEN-E show the details.

6Your European tax number on US forms

The US forms call it the Foreign Tax Identifying Number, or FTIN. It means the number your country of residence assigned you for income tax, or for a company, the number under which it is taxed there. On the W-8BEN it goes on line 6a, on the W-8BEN-E on line 9b.

Two rules from the instructions matter. First, you can give the FTIN instead of a US number to claim treaty benefits. If you do, you need no ITIN for that purpose, and the company needs no EIN. Second, the FTIN becomes mandatory if you use the form to document an account at a US branch of a financial institution and receive US-source income on it that is reported on Form 1042-S. Exceptions apply, among others, if your country of residence is on the IRS list of countries that do not issue tax numbers, or if the law of your country does not require you to have one; that is what box 6b on the W-8BEN is for.

The tax number from your country of residence only replaces the US number on these certificates, though. Your own US return, Form 1040-NR or Form 1120-F, always requires a US number.

7Confirm, change, lose

If you have misplaced your EIN confirmation, the IRS says you can request an entity transcript, download it as digital notice CP575 in your Business Tax Account, or ask for letter 147C by phone. If a return is due before the EIN arrives, the IRS says to write "Applied For" and the application date in the number field.

For the ITIN, notice CP565 is the confirmation. If your name changes, for example through marriage, write to the ITIN office in Austin and enclose proof. If you move before the ITIN is issued, give the IRS your new address so the notice and your original documents reach you. If you have several numbers, such as an EIN for the business and an ITIN for yourself, the regulations say to list the number already issued on the other application so the IRS can link the two.

In short

• TIN is the umbrella term. The three numbers that almost always matter are the EIN for companies, and the ITIN and SSN for individuals.
• The IRS issues the EIN free of charge; without an SSN or ITIN for the responsible party, you cannot apply online, only by fax, mail or, for international applicants, by phone.
• You apply for the ITIN with Form W-7, usually together with a tax return; the IRS quotes seven weeks, or nine to eleven from abroad.
• Only US citizens, green card holders or people authorized to work in the USA get an SSN; you cannot hold an ITIN and an SSN at the same time.
• On many US forms, the tax number from your country of residence can replace the US number.

How we help you

• ITIN ExpressYour ITIN through our special procedure, no tax return needed.
• Apply for an EINYour company's US tax ID, applied for by us.
• Your US Tax ReturnForm 1040 or 1040-NR, handled in English.
• US Tax ConsultationYour US tax question, answered by people who know both sides.