An ITIN is a nine-digit number that the IRS gives to people who have to be identified on a U.S. federal tax filing but cannot get a Social Security number. The IRS calls it "a tax processing number." It begins with the digit 9 and it is written the same way an SSN is written: NNN-NN-NNNN.
Two mistakes send founders here. The first is thinking that an ITIN is a general permission slip, so they apply for one before they need it, or they believe they must have one before they can register a company or get an EIN. The second is the opposite: they assume the number is out of reach, so they never apply, and then a tax filing that requires a number for them personally has nowhere to put one.
There is one rule underneath all of this, and it is short. If you are eligible for a Social Security number, you cannot get an ITIN. The two numbers do not overlap. Notice that this test is about SSN eligibility, not about your passport and not about whether the IRS counts you as a U.S. person. Those are different questions, and they do not always give the same answer.
What the rule actually says
The IRS keeps five kinds of taxpayer identification number: the SSN, the EIN, the ITIN, the ATIN (for pending adoptions) and the PTIN (for paid preparers). The Social Security Administration issues the SSN. The IRS issues all of the others, including the ITIN.
The IRS describes the ITIN as "a tax processing number only available for certain nonresident and resident aliens, their spouses, and dependents who cannot get a Social Security Number (SSN)."
Two words in that sentence do the work.
The first is cannot. The number exists for people who are shut out of the SSN system. The IRS lists the people who do not need an ITIN, and the list is exactly the people who can get an SSN:
- a U.S. citizen,
- a permanent legal resident of the United States (a green card holder),
- a nonresident alien with a U.S. work visa, "since you qualify for an SSN," and
- more generally, "anyone eligible for an SSN."
The second is certain. Being outside the SSN system is not, on its own, a reason to apply. You apply because a U.S. federal tax filing requires a number for you. The IRS puts it this way on the Form W-7 page: the ITIN goes to people "who are required for U.S. federal tax purposes to have a U.S. taxpayer identification number but who do not have and are not eligible to get a Social Security number (SSN)."
Immigration status does not decide it. The IRS is explicit: "If you're a resident alien, nonresident alien or their spouse or dependent, you can apply for an ITIN regardless of immigration status."
What an ITIN does not do
The IRS lists the limits directly. An ITIN does not:
- qualify you for Social Security benefits or the Earned Income Tax Credit,
- provide or change immigration status,
- authorize you to work legally in the United States, or
- serve as identification outside the federal tax system.
Read that last item as a practical warning. The number is for tax filings. It is not a national ID, and no bank, landlord or state agency has to accept it for anything.
How you get one, and how long it takes
You apply on Form W-7, by mail or in person. Mailed applications go to the IRS ITIN Operation in Austin, Texas. The same Form W-7 is also used to renew "an existing ITIN that is expiring or that has already expired," so you do not learn a second form later.
The timing is the part people plan badly. The IRS asks you to "allow 7 weeks for us to notify you about your ITIN application status," and says "it can take 9-11 weeks if it's tax season (January 15 to April 30) or if you applied from overseas."
Do the arithmetic before you file. If you are outside the United States and you send Form W-7 in the first week of March, you are inside both slow cases at once. Count 9 to 11 weeks from early March and the notice reaches you somewhere between the first week of May and the last week of May. If your filing depends on having the number, you needed to start in January, not March.
ITIN and EIN are not the same number
An EIN, in the IRS's own words, "is used to identify a business entity." An ITIN identifies a person. A company gets an EIN. A human being who cannot get an SSN gets an ITIN. They are issued for different purposes and one is not a step toward the other. Whether your particular company filings also require a personal number for you is a separate question, and you should check it rather than assume the answer in either direction.
🇺🇸 If the IRS counts you as a U.S. person
Start by separating two things that sound alike.
"U.S. person for tax purposes" is decided by the green card test and the substantial presence test. "Eligible for an SSN" is decided by the Social Security Administration, and it usually follows from citizenship, permanent residence or work authorization. The ITIN question is decided by the second one, not the first.
For most U.S. persons this makes no difference. A citizen has an SSN. A green card holder has an SSN, or is eligible for one. Either way, the answer is the same: you cannot apply for an ITIN, and the IRS says you do not need one.
The case that surprises people is the resident alien who is not eligible for an SSN. You can become a U.S. resident for tax purposes purely by counting days under the substantial presence test, without ever holding work authorization. In that situation the IRS treats you as a U.S. person for tax, and you still use an ITIN, because the SSN door is closed to you. The IRS says so plainly when it lists "resident aliens" among the people who may apply, "regardless of immigration status."
One more limit applies inside this lane. If you file with an ITIN, you cannot claim the Earned Income Tax Credit. Being a U.S. person for tax does not restore that credit.
🌏 If it does not
Ask first whether you actually need the number. The test is whether a U.S. federal tax filing requires a taxpayer identification number for you personally. Form W-7 makes you tick a box saying which reason applies to you, and the list of reasons is the list of people the IRS expects to see. It includes a nonresident alien claiming a tax treaty benefit, a nonresident alien filing a U.S. federal tax return, a resident alien filing a return on the basis of days present, and the spouse or dependent of a U.S. citizen or resident alien. The instructions also say that an application for a new ITIN has to include a U.S. federal tax return unless you meet one of the listed exceptions, which is the same rule stated from the other side: the filing comes first, and the number follows it.
Owning a U.S. company is not by itself on that list. Your company can hold an EIN in its own name. Whether your own filings then require a number for you depends on what you are filing, so check that against the specific form rather than assuming that company ownership settles it.
If you do need one, plan around the calendar. Applying from overseas puts you in the 9 to 11 week window on its own, and applying during tax season does the same. Doing both at once does not make the wait shorter.
Finally, do not expect the number to travel outside the tax system. It will not authorize work, it will not change your immigration status, and the IRS says it does not serve as identification outside federal tax. If you were hoping the ITIN would help you open an account or prove who you are somewhere else, that is not what it is.
Where the two lanes split
The two lanes give different answers to the first question and identical answers to almost everything after it. The dividing line is SSN eligibility, not the U.S.-person test, which is why parts of this table are the same on both sides.
| Question | 🇺🇸 U.S. person | 🌏 Not a U.S. person |
|---|---|---|
| Can you apply for an ITIN? | Only if you are not eligible for an SSN. Citizens and green card holders are eligible, so for them the answer is no | Yes, if you cannot get an SSN and a U.S. tax filing needs a number for you |
| What decides it | SSN eligibility, not your tax residency | SSN eligibility, not your nationality |
| Which form | Form W-7 | Form W-7 |
| Who issues the number | The IRS | The IRS |
| Processing time | Allow 7 weeks; 9 to 11 weeks in tax season | Allow 7 weeks; 9 to 11 weeks in tax season or from overseas |
| Does it authorize work? | No | No |
| Earned Income Tax Credit | Claimed with an SSN, never with an ITIN | Not available with an ITIN |
Common mistakes
🇺🇸 If the IRS counts you as a U.S. person
- Applying for an ITIN while holding an SSN, or while eligible for one. The IRS lists you as someone who does not need an ITIN, and the application will not give you a second number.
- Assuming that passing the substantial presence test gets you an SSN. It does not. Residency for tax and eligibility for an SSN are decided by two different agencies under two different rules.
- Filing with an ITIN and claiming the Earned Income Tax Credit. The IRS states that you cannot claim it with an ITIN.
🌏 If it does not
- Applying before you know you need the number. The ITIN is for people who are required to have a U.S. taxpayer identification number for federal tax purposes, not for anyone who wants one.
- Applying in March from another country and expecting an answer in weeks. Both of those facts push you into the 9 to 11 week window.
- Treating the ITIN as identification. The IRS says it does not serve as identification outside the federal tax system and does not authorize you to work.
- Confusing it with the company's EIN. The EIN identifies a business entity. The ITIN identifies a person.
FAQ
Who is eligible for an ITIN?
Certain nonresident aliens and resident aliens, and their spouses and dependents, who cannot get a Social Security number and who are required to have a U.S. taxpayer identification number for federal tax purposes. The IRS says you can apply "regardless of immigration status."
Can I get an ITIN if I already have an SSN?
No. The IRS lists a U.S. citizen, a green card holder, a nonresident alien with a U.S. work visa and "anyone eligible for an SSN" as people who do not need an ITIN. The two numbers are alternatives, not a pair.
Do I need an ITIN to own a U.S. company or to get an EIN?
Those are different numbers with different jobs. An EIN identifies a business entity. An ITIN identifies a person who cannot get an SSN. Whether your own tax filings require a personal number depends on what you have to file, so check the specific form instead of assuming.
How long does an ITIN application take?
The IRS asks you to allow 7 weeks to be notified of your application status. It can take 9 to 11 weeks during tax season, which the IRS defines as January 15 to April 30, or if you applied from overseas.
Which form do I use, and does it also renew an expired ITIN?
Form W-7 in both cases. The IRS says the form is used to apply for a new ITIN and also "to renew an existing ITIN that is expiring or that has already expired."
Does an ITIN let me work in the United States?
No. The IRS states that an ITIN does not authorize you to work legally in the United States, does not provide or change immigration status, and does not serve as identification outside the federal tax system.
Can I claim the Earned Income Tax Credit with an ITIN?
No. The IRS says an ITIN does not qualify you for Social Security benefits or the Earned Income Tax Credit, and it repeats on its taxpayer number page that you cannot claim the earned income credit using an ITIN.