ID number in the United States: SSN vs ITIN

If you are relocating to the US, you will usually need an ID number to work, pay taxes, and access certain government benefits such as pensions. The two key numbers used in the US are the Social Security Number (SSN) and the Individual Taxpayer Identification Number (ITIN).

This guide explains what these numbers are, who needs them, when you can usually apply, and what they are used for. It also covers other documents you may be asked to provide by organizations such as banks and landlords, including proof of identity, address, and immigration status.

Note: This article is for general information only and doesn’t constitute official tax, legal, immigration, or financial advice. Always verify the latest rules with the Internal Revenue Service, the Social Security Administration, or the institution asking for your number.

Key takeaways

What people mean by an ID number in the United States

In the US, there is not one single ID number that covers everything. The meaning of “ID number” depends on the form, organisation, or situation.

For tax filing purposes, your ID number refers to your Taxpayer Identification Number (TIN), which is the umbrella term used by the Internal Revenue Service (IRS) to cover Social Security Number (SSN) and Individual Taxpayer Identification Number (ITIN).

However, banks, employers, landlords, and government agencies may ask for different numbers or documents depending on their requirements. They may also request proof of identity, address, or immigration status.

📌 In practice, “ID number” often means one of these things:

• Your SSN for employment, payroll, taxes, aocial security records, and many federal forms
• Your ITIN if you have a federal tax filing need but are not eligible for an SSN
• A state identity number, such as from a driver’s license or state ID, which is not the same as an SSN or ITIN
• Alien Registration Number (A Number), which is an immigration number assigned to many non-citizens by USCIS
• Passport number used for identity verification when travelling abroad

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SSN vs ITIN at a glance

A common question is whether SSN and ITIN are interchangeable. The short answer is no. They serve different purposes, even though both may appear on tax paperwork.

Some people receive an ITIN first and later become eligible for an SSN. If this happens, you should use your SSN going forward and notify the IRS so your records can be updated. You generally should not use both numbers at the same time.

Which number do expats need?

The key question is not “What is the ID number in the US?” but “What do I need to do?” Your immigration status, work authorization, and tax situation determine which number, if any, you need.

This differs from many countries where a single government-issued number is used for most official purposes. In the US, employment, tax, immigration, and banking rules overlap but are not identical, which is why newcomers often get mixed messages.

➡️ Use this quick checklist to decide what to do next:

• Employee with work authorization: You will usually need an SSN. Check the SSA route tied to your visa or status and prepare to apply once you are eligible.
• Spouse or dependent: You may need an ITIN if you have a federal tax filing or reporting requirement and cannot get an SSN. Check IRS eligibility before sending any application.
• Student or scholar: Some people qualify for an SSN, while others only need an ITIN for tax reporting. Read the rules linked to your school, visa, and SSA or IRS guidance.
• Tax filing need only: If you are not eligible for an SSN but must file a federal return or claim an allowed tax benefit, an ITIN may be the right path.
• Still abroad and planning the move: Do not assume you can complete everything before travel. Check whether you should apply for an SSN after arriving in the US or whether you can start an ITIN application from abroad.

How to get an SSN

An SSN is issued by the Social Security Administration (SSA) and is generally for people who qualify under citizenship or immigration rules.

Because eligibility depends on status, the safest approach is to use the official SSA first-time number request page and the guidance linked from it for noncitizens, students, or foreign workers.

Before you move

First-time SSN applications are generally handled once you are in the US. If your visa or immigration process includes SSN-related instructions, follow those exactly and check the latest SSA rules before you travel, because physical presence and status verification are commonly part of the process.

After you arrive

1. Start the first-time request through the SSA and check whether you can begin online before visiting an office. 
2. Gather the documents the SSA asks for, which can include proof of identity, age, and citizenship or lawful immigration status. The exact list depends on your status. 
3. Go to the local Social Security office if the process for your case requires an in-person step, and confirm local office procedures before you visit. 
4. After approval, the SSA will mail your Social Security card to you. The SSA says this usually takes 7 to 10 business days after approval.

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How to get an ITIN and can you apply from abroad?

An ITIN is for people who need a US taxpayer identification number for federal tax purposes but are not eligible for an SSN. That makes it common for noncitizens with a filing obligation, certain spouses or dependents, and some people claiming treaty benefits or other allowed tax positions through the IRS.

Documents and application routes

You can apply for an ITIN with Form W-7, usually alongside a federal tax return unless an exception applies.

The IRS also explains that some applicants can use the ITIN from abroad guidance if they are outside the US.

💡 Before you apply, check these points:

• You will need supporting documents to prove your identity and foreign status
• A passport can usually stand alone, while other forms of ID may need accompanying documents
• You may apply by mail, through an IRS-authorized Certifying Acceptance Agent, or at an IRS Taxpayer Assistance Center
• If you may need your original documents soon, verify whether certified copies from the issuing agency or an in-person route is better before you send anything

Timing, renewal, and switching to SSN

The IRS says ITIN processing usually takes 7 weeks, or 9 to 11 weeks during peak tax season or if you apply from overseas.

⚠️ An ITIN can expire if it is not used on a federal return for three consecutive tax years, and if you later receive an SSN, you should stop using the ITIN for tax purposes and notify the IRS so your records can be aligned.

Where expats may be asked for an ID number

You may be asked for an SSN or ITIN when filing taxes, starting a job, or opening a US bank account. If you are looking to open a bank account, remember that the number itself may not be enough.

US banks may also ask for proof of address, visa or immigration paperwork, or evidence of employment.

If you are waiting on local paperwork when you first arrive, you can also consider multi-currency account options such as Wise Account.

Wise supports 40+ currencies for hold & exchange, and you can get local account details for USD to receive payments, send money to 160+ countries, and spend with the linked debit card.

If you have not moved to the US yet, you might still be able to open a Wise Account, and start holding money in USD and get the local account details. Wise products and features availability may vary based on location, here you can check the Wise Account availability for your current residence country.

💡 You may be asked for an SSN when you:

• Start a job and complete payroll or tax forms
• File a federal tax return or claim Social Security or Medicare benefits
• Open a bank account or apply for financial products such as credit or insurance
• Rent a home, set up utilities, or apply for a driver’s license

Writer

Gary Buswell

Insider tip

Some US banks such as Chase, Bank of America, and Wells Fargo branches may accept an ITIN in some situations, but the bigger problem is often proof of a US address or residence.

Make sure to confirm with your local branch before making your application.

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FAQs about ID number in the United States

What is the ID number in the United States?

There is no single official ID number in the US. In practice, it usually means an SSN for work and many admin tasks, or an ITIN for tax paperwork. In other situations, an “ID number” could instead mean a driver’s licence number, state ID number, passport number, or immigration number (such as an Alien Registration Number).

Is an ID number the same as SSN?

Not always. An SSN is one form of ID number. People often use “ID number” as a shortcut, but the form may actually be asking for an SSN, an ITIN, or another document, so read the request carefully before you apply.

Can a non-US citizen get a tax ID?

Yes, in some cases. A non-US citizen may be able to get an ITIN if they have a valid federal tax filing or reporting requirement and are not eligible for an SSN. However, an ITIN is not a general everyday identity document.

Can I use my SSN instead of TIN?

Yes, because an SSN is one type of TIN in the US tax system. If you used an ITIN before and later receive an SSN, follow the IRS steps to stop using the ITIN for tax purposes and align your records.

Useful resources

(checked on 20th July 2026)

• IRS guide to taxpayer identification numbers
• IRS ITIN overview and eligibility rules
• IRS guidance on obtaining an ITIN from abroad
• SSA first-time Social Security number request page