SSN vs ITIN — What Immigrants Need to Know for Taxes

Two Numbers That Determine How You File

When we begin navigating the U.S. financial and tax system, one of the first confusing moments involves a simple question that appears on almost every important form: “What is your taxpayer identification number?”

For people who grew up in the United States, this question has an automatic answer. They have had a Social Security Number since childhood. The question barely registers.

For many of us, it stops everything. Do you need a Social Security Number to file taxes? Can you use an ITIN instead? Are they the same thing? Can you have both?

These questions matter enormously. Getting the wrong answer can mean filing taxes incorrectly, missing refunds you are entitled to, or creating complications that affect both your finances and your immigration case.

This guide will explain the difference between the two numbers, who needs each one, how to get them, and exactly how they affect the way we file taxes in the United States.

What Is a Social Security Number?

A Social Security Number — or SSN — is a nine-digit number issued by the U.S. Social Security Administration. It was originally created to track workers’ earnings and calculate retirement benefits. Over time, it has become the primary identification number used across the entire American financial and administrative system.

Your SSN is used for filing federal and state tax returns, opening bank accounts, applying for credit cards and loans, employment verification, and accessing government benefits.

Who is eligible for an SSN:

Social Security Numbers are issued to U.S. citizens, U.S. nationals, and certain immigrants authorized to work in the United States. This includes lawful permanent residents (green card holders) and immigrants authorized to work on certain visa types such as H-1B, L-1, O-1, TN, E-3, and others.

If you are authorized to work in the United States, you are generally eligible to apply. Applications are made through the Social Security Administration with documentation of your identity, age, and immigration status.

When you cannot get an SSN:

Not all immigrants are eligible. If you are in the United States but not authorized to work — on certain visa types, a tourist visa, or in an undocumented status — you are not eligible for an SSN.

This does not mean you have no tax obligations. Many people without an SSN still have income in the United States and are required by law to file tax returns. For these situations, the IRS created a separate identification number: the ITIN.

What Is an Individual Taxpayer Identification Number (ITIN)?

An ITIN is a nine-digit number issued by the IRS specifically for tax purposes. It is for individuals who have a U.S. tax filing obligation but are not eligible for a Social Security Number.

ITINs always begin with the number 9, which distinguishes them from Social Security Numbers.

Who uses an ITIN:

• Immigrants who have U.S. income but are not authorized to work
• Undocumented immigrants who earn income and are required to pay taxes
• Foreign nationals with U.S. tax obligations due to investments or rental income but who do not live here
• Spouses and dependents who need to be listed on a tax return but are not eligible for an SSN

What an ITIN is used for:

An ITIN is used exclusively for tax purposes. It allows people without SSNs to file federal tax returns, pay taxes on U.S.-source income, be claimed as a dependent on another person’s return, and open certain bank accounts or apply for certain financial products.

What an ITIN cannot do:

An ITIN is not a work authorization document. It cannot be used to verify employment eligibility, obtain a Social Security card, or establish immigration status. It does not entitle the holder to Social Security benefits or the Earned Income Tax Credit in most circumstances.

A Critical Point: Everyone With U.S. Income May Have a Tax Obligation

This is one of the most important things for us to understand about the U.S. tax system.

Your obligation to pay taxes is based on your income — not your immigration status or documentation.

Many immigrants believe incorrectly that without a Social Security Number, or without documentation, they do not need to pay taxes. In fact, the IRS requires anyone with income above certain thresholds to file a return and pay applicable taxes, regardless of immigration status.

The IRS and immigration authorities are separate agencies. The IRS’s role is tax collection, not immigration enforcement. Filing a tax return does not trigger immigration consequences. In fact, filing taxes often creates a documented record of presence and compliance that can support immigration applications.

The ITIN exists specifically to allow people without SSNs to meet their tax obligations legally.

How to Apply for a Social Security Number

If you are eligible for an SSN, applying for one is an important early step.

Applications are made at your local Social Security Administration (SSA) office. You can find the nearest location on the SSA website.

You will need proof of identity such as a passport, proof of your immigration status and work authorization such as your visa or I-94 arrival record, and proof of age. All documents must be originals or certified copies — photocopies are not accepted.

Some immigrants are able to request an SSN as part of the visa application process. Others must apply after arriving. In general, wait until you have arrived and your immigration documents are current before applying.

Processing typically takes two to four weeks from the date of your application.

How to Apply for an ITIN

If you are not eligible for a Social Security Number but have U.S. tax obligations, applying for an ITIN is a necessary step.

The application form: IRS Form W-7 — “Application for IRS Individual Taxpayer Identification Number.” Available on the IRS website.

What to submit: You must prove two things — your foreign status and your identity. A passport is the most straightforward document because it proves both at once. You must also typically submit a completed federal tax return with your W-7 application, unless you qualify for one of the specific exceptions listed on the form.

Three ways to submit:

By mail. Send your completed Form W-7, your tax return, and your original identity documents to the IRS ITIN Operations center. Note that mailing original documents carries some risk — documents can be lost. Use this option with care.

In person at an IRS Taxpayer Assistance Center. Staff can review and certify your documents on the spot, so you do not have to mail originals.

Through a Certified Acceptance Agent (CAA). A Certified Acceptance Agent is a person or organization authorized by the IRS to assist with ITIN applications. They can review your original documents, certify copies, and submit the application on your behalf. Many tax preparation services, community organizations, and legal aid organizations are Certified Acceptance Agents. This is often the most practical option for us.

Processing typically takes seven to eleven weeks during tax season, less during off-peak periods.

ITIN expiration: ITINs can expire if not used on a federal tax return for three consecutive years, or due to IRS changes to certain ITIN ranges. Check whether your ITIN is still current before filing. If it has expired, you will need to renew it first.

What Happens If You Get an SSN After Having an ITIN?

This is a common situation for immigrants whose status changes.

When you receive an SSN, notify the IRS so your prior tax filings can be associated with your new number. Write to the IRS providing both your ITIN and your new SSN. Once your records are updated, use your SSN going forward and no longer use your ITIN. Notify your employer and any financial institutions as well.

The Earned Income Tax Credit and ITIN

One important limitation of the ITIN is worth understanding. People who file taxes using an ITIN are generally not eligible for the Earned Income Tax Credit (EITC).

The EITC is a significant tax benefit for lower and moderate-income workers. For workers with children, it can be worth thousands of dollars per year. It is available only to people who file with a valid Social Security Number.

If you have been filing with an ITIN but later obtain an SSN, you may be able to go back and claim the EITC for prior years. The rules are specific — a tax professional can help you determine whether you qualify for any back credits.

Children of Immigrants: SSN vs. ITIN

Children born in the United States are U.S. citizens and eligible for Social Security Numbers at birth. You can request an SSN for your child at the hospital or afterward through the Social Security Administration.

Children born outside the United States who do not qualify for an SSN can be listed on a parent’s tax return using an ITIN, if they meet dependency requirements. Make sure you have the correct identification number — SSN or ITIN — for each child you claim as a dependent.

Protecting Your SSN and ITIN

Both numbers are sensitive pieces of personal information. In the wrong hands, they can be used for identity theft and financial fraud.

Do not carry your Social Security card in your wallet — keep it in a secure place at home. Do not share your SSN or ITIN over the phone or by email unless you initiated the contact with a trusted institution.

Be aware of IRS impersonation scams. The IRS primarily communicates by mail. If someone calls claiming to be from the IRS and demands immediate payment or personal information, this is almost certainly a scam. Hang up and contact the IRS directly using the number on their official website.

Review your tax transcripts annually to ensure no one has filed a fraudulent return using your identification number.

The Right Number Makes Everything Easier

Understanding the difference between an SSN and an ITIN, knowing which one applies to your situation, and having the correct number before tax season begins makes the entire filing process significantly simpler.

If you are eligible for a Social Security Number, apply as soon as possible. If you are not eligible and have U.S. income or tax obligations, apply for an ITIN using Form W-7 before you need to file your first return.

In our next guide, we walk through the complete step-by-step process of filing your taxes as an immigrant in the United States — from gathering your documents to submitting your return.