Do I Need an ITIN or a Social Security Number?

Hayden McCoy, CFE, EA, CTC, CFP®

Aug 9

6 min read

If you are eligible for a Social Security Number (SSN), you generally should not apply for an ITIN instead. An ITIN is for foreign individuals who need a U.S. taxpayer identification number for tax purposes but are not eligible for an SSN.

The question sounds simple, but it can become confusing for foreign spouses, children born outside the United States, students, workers, and military families.

What Is the Difference Between an ITIN and an SSN?

A Social Security Number is issued by the Social Security Administration. It is commonly issued to U.S. citizens, lawful permanent residents, and certain noncitizens who are authorized to work in the United States.

An Individual Taxpayer Identification Number, or ITIN, is issued by the IRS. It is used for federal tax purposes by people who need a U.S. taxpayer identification number but are not eligible for an SSN.

The two numbers are not interchangeable.

An ITIN does not:

Authorize you to work in the United States
Change your immigration status
Make you eligible for Social Security benefits
Replace an SSN if you qualify for one

Who May Need an SSN?

You may be eligible for an SSN if you are:

A U.S. citizen
A lawful permanent resident
A noncitizen with qualifying U.S. work authorization
Otherwise eligible under Social Security Administration rules

If you are clearly eligible for an SSN, an ITIN is generally not the correct number to apply for - it will be rejected.

If you are unsure whether your immigration or work status makes you eligible for an SSN, that question should be resolved before filing Form W-7 for an ITIN.

In some ITIN exception cases, the IRS may also require proof that you are not eligible for an SSN. This can include a denial or rejection notice from the Social Security Administration. If that documentation is required for your situation, it must be obtained before the ITIN application can be completed correctly.

Who May Need an ITIN Instead?

An ITIN may be appropriate when you have a valid U.S. tax reason but are not eligible for an SSN.

Common examples include:

A foreign spouse of a U.S. taxpayer
A qualifying foreign child or dependent
A foreign individual receiving U.S.-source income
Someone who had U.S. tax withheld and needs to claim a refund
A foreign owner of U.S. rental property
A foreign seller of U.S. real estate
A foreign individual starting or operating a U.S. business
Someone who qualifies under a specific IRS-approved exception

The key question is not simply, "Do I need a tax number?"

It is: Which tax identification number am I actually eligible for?

What About a Foreign Spouse?

A foreign spouse who is not eligible for an SSN may need an ITIN if they have a valid reason to be included on a U.S. tax return.

Raj is on an H-1B visa, working in the United States. Because his visa authorizes him to work, he was eligible for and received a Social Security Number himself. His wife, on an H-4 visa without independent work authorization, was not. To elect to file jointly and claim any tax benefits available from that filing position, his wife needed an ITIN instead — since her visa status, not her nationality, was what made her ineligible for an SSN. Without making that election, Raj could not file Married Filing Jointly with his nonresident spouse — and Married Filing Jointly is often the more favorable filing status, though it also brings the spouse into the U.S. tax system.

That last part matters: choosing to include a foreign spouse in the U.S. tax system can create future U.S. filing and reporting obligations. That's why the decision should be made carefully. The ITIN itself is only one part of the process.

What About Children Born Outside the United States?

Children are different and require more careful consideration.

A child born outside the United States may be eligible for a Social Security Number through a U.S.-citizen parent, depending on the child's citizenship status and the applicable rules.

But parents living abroad may have important personal and tax decisions to make before choosing whether to document the child's U.S. status and obtain an SSN.

Applying for an SSN does not itself create U.S. citizenship. However, if the child already acquired U.S. citizenship at birth, obtaining an SSN may make that status more visible in the U.S. tax system and can have long-term consequences that parents should understand.

For some families, especially those living permanently outside the United States, this can be a significant decision.

If the child is not eligible for an SSN but needs a U.S. taxpayer identification number for a qualifying tax purpose, an ITIN may be appropriate instead — though most dependent ITIN applications also require proof that the child has actually been physically present in the United States, which is its own hurdle for families living abroad.

Joseph is a U.S. citizen who served as a missionary abroad. He married a foreign spouse, who received an ITIN of her own. Several years later, they had a child together. The child was not eligible for an ITIN until Joseph and his wife brought her for a visit to the United States and had an entry date stamped in her passport — proof of the physical presence the IRS required before the dependent ITIN application could move forward.

The tax benefits available may also differ depending on whether the child has an SSN or an ITIN, so this is not a decision that should be made casually.

A Note for Military Families

U.S. military families with foreign spouses or children can face particular challenges with this question.

A service member stationed overseas may have:

Married a foreign national
Had a child outside the United States
Moved between countries before completing U.S. identification paperwork
Limited access to qualified tax assistance
A filing deadline while also dealing with deployment or relocation

If a foreign spouse or child does not have the correct identification number, the service member may be unable to file using the correct family information.

That can affect:

Filing status
Available tax benefits
Credits
Refunds
The amount of tax owed

The first question should not automatically be: "How do we get an ITIN?"

It should be: "Is this spouse or child eligible for an SSN, or is an ITIN the correct number?"

Getting that answer right at the beginning can prevent rejected applications and incorrect tax returns later.

Can I Choose an ITIN Instead of an SSN?

Usually, no.

An ITIN is not simply an alternative tax number you can choose because it seems easier or because you only need a number for tax purposes.

If you are eligible for an SSN, the IRS generally expects you to obtain the SSN instead.

You should not apply for an ITIN merely because:

You do not want an SSN
You think an ITIN will be easier
You only need the number for a tax return
You were told by someone unfamiliar with the rules that an ITIN is "good enough"

Eligibility comes first.

What If I Already Have an ITIN and Later Become Eligible for an SSN?

This can happen.

For example, a foreign spouse may initially qualify only for an ITIN and later receive immigration status or work authorization that makes them eligible for an SSN.

When that happens, there is a specific process for transitioning from the ITIN to the SSN so prior tax records are handled correctly.

We will cover that process in a separate article: What Happens to My ITIN If I Later Get a Social Security Number?

Why This Question Matters Before You Apply

A perfectly prepared Form W-7 will not solve the problem if the applicant should have been applying for an SSN instead.

At ITIN Abroad, one of the first things we consider is whether the applicant may be eligible for a Social Security Number.

In some cases, simply stating that you are not eligible for an SSN is not enough. The IRS may require documentation from the Social Security Administration confirming that an SSN was denied.

If SSN eligibility is unclear, it may need to be confirmed before the ITIN process moves forward.

The goal is not simply to obtain a number. The goal is to obtain the correct number for your situation.

FAQ

Can my foreign spouse get an ITIN?

Possibly. If your spouse has a valid U.S. tax reason and is not eligible for an SSN, an ITIN may be appropriate.

My child was born outside the United States. Do they automatically need an ITIN?

No. First determine whether the child may be eligible for an SSN. Children born abroad can have very different circumstances depending on citizenship and family history.

Does an ITIN allow me to work in the United States?

No. An ITIN is used for tax purposes only. It does not provide employment authorization.

Can I have both an ITIN and an SSN?

Your situation can change over time. If you later become eligible for and receive an SSN, there is a specific process for transitioning your tax records from the ITIN to the SSN.

What if an ITIN exception requires proof that I cannot get an SSN?

Some exceptions require documentation showing that you are not eligible for an SSN. Depending on the situation, this may include a rejection or denial notice from the Social Security Administration.

What if I am not sure which one I qualify for?

Do not guess. Determine SSN eligibility first. If you are not eligible for an SSN but have a valid U.S. tax reason, an ITIN may be the correct path.

An ITIN and an SSN may both be used on U.S. tax returns, but they serve different purposes. The right starting point is not "Which one do I want?" but "Which one am I actually eligible for?"