Overview

If you’re new to the U.S. or your situation changed this year, choosing between an ITIN and an SSN affects how you file taxes, claim credits, get paid, and open bank accounts. This guide focuses on Itin Vs Ssn so you can decide quickly, apply correctly, and manage either number with confidence in 2025.

In short, use an SSN if you’re eligible. Use an ITIN only if you are not eligible for an SSN but must be on a U.S. tax return or related form. Some credits require SSNs; if you later get an SSN, tell the IRS so your ITIN history is merged.

What is the difference between an ITIN and an SSN?

An ITIN is a tax-processing number the IRS issues for people who are not eligible for an SSN but need to file or be listed on a U.S. tax return, while an SSN is issued by the Social Security Administration for wage reporting, benefits, and identity verification. See the IRS ITIN page and the SSA Number & Card guidance for official definitions and uses.

In practical terms, the IRS issues ITINs strictly for tax administration; the SSA issues SSNs for employment and benefits reporting. Employers and payroll systems typically require SSNs; the IRS accepts ITINs when an SSN isn’t available or allowed.

How do their purposes, issuers, and eligibility compare?

The IRS issues ITINs to support U.S. tax filing and information reporting when someone is not eligible for an SSN; apply using Form W‑7. The SSA issues SSNs to U.S. citizens, lawful permanent residents, and noncitizens with valid work authorization using Form SS‑5.

An ITIN does not authorize work. An SSN does not, by itself, grant work authorization; immigration documents establish employment eligibility. If you’re SSN‑eligible, apply for an SSN; if not, but you must file or be listed on a tax return, apply for an ITIN.

Why does choosing the right number matter for taxes, benefits, and employment?

Choosing the correct number determines whether your return is accepted, whether you can claim certain credits, and how wages and withholding are reported. Payroll, banking, and program systems validate SSNs for employment and benefits while the IRS accepts ITINs for non‑SSN tax reporting.

For example, the Earned Income Tax Credit requires valid SSNs for the taxpayer, spouse, and qualifying children, and the Child Tax Credit requires that qualifying children have SSNs by the return due date; see the IRS EITC and Child Tax Credit pages for details. Using the wrong number can lead to rejects, missed benefits, or withholding mismatches.

Which credits and forms are affected?

Credits that hinge on SSNs include the Earned Income Tax Credit and the Child Tax Credit, both of which have SSN requirements for claimants and qualifying children. The IRS provides eligibility rules and SSN requirements on its EITC and Child Tax Credit pages.

An ITIN is acceptable for filing a federal tax return when you are not SSN‑eligible, for being listed on another person’s return, or for certain withholding or treaty forms. If you need employment-related reporting or SSN‑based credits, you must obtain an SSN.

Who qualifies for an SSN versus who needs an ITIN?

U.S. citizens, lawful permanent residents, and noncitizens authorized to work generally qualify for an SSN through the SSA; people not eligible for an SSN but who must file a U.S. tax return or be listed on a U.S. tax form need an ITIN from the IRS.

Common ITIN cases include nonresident filers, certain dependents or spouses of U.S. taxpayers, and individuals receiving U.S.‑source income who must be identified to the IRS but aren’t SSN‑eligible. If you have work authorization or plan to work, obtain an SSN for payroll and benefits reporting.

What special cases apply to international students, spouses, and dependents?

International students (F‑1/J‑1) normally need an SSN only if they have on‑campus employment or authorized off‑campus work; without work, they may need an ITIN to file a return or claim a treaty benefit. Spouses and dependents who are not SSN‑eligible often use ITINs to be listed on returns.

For example, an F‑1 student with a taxable scholarship but no employment cannot get an SSN for that purpose and would apply for an ITIN to file correctly and claim treaty benefits where applicable. A nonresident spouse without work authorization who files jointly with a U.S. taxpayer typically uses an ITIN.

What are your options if your situation changes during the year?

If you become SSN‑eligible midyear (for example, you receive work authorization), apply for an SSN promptly and stop using the ITIN; then notify the IRS so your records are merged. Timing matters to avoid withholding, credit, and reporting mismatches.

If you move from nonresident to resident status or begin employment, get your SSN as soon as eligible and use it for wage reporting and future filings to prevent mismatches and credit issues.

How do you move from an ITIN to an SSN and combine your records?

After you receive your SSN, use it on all future tax returns and discontinue use of the ITIN. Then write a brief letter to the IRS including your full name, prior ITIN, new SSN, and a request to combine your tax records; follow any directions on IRS correspondence or the IRS ITIN page and keep copies of SSA notices and mail confirmations for your records.

What does it cost and how long does it take?

There is no government filing fee to apply for either an ITIN or an SSN; the IRS’s Form W‑7 guidance and the SSA Number & Card page confirm that the government does not charge an application fee. Processing times vary by season and method, and third‑party Certified Acceptance Agents may charge separate service fees for document review or submission.

Plan for several weeks for IRS ITIN processing and typically a shorter timeframe for SSA SSN issuance once documentation is complete; submit early if you are near filing deadlines.

Where can you get in-person help or certified copies?

You can book an appointment at an IRS Taxpayer Assistance Center for in‑person identity verification to avoid mailing original documents; use the IRS TAC locator to find local offices. Another option is a Certified Acceptance Agent (CAA), who is authorized by the IRS to review documents and submit your W‑7 package on your behalf; see the IRS Acceptance Agent Program directory for authorized agents.

For SSN applications, many SSA offices allow or require appointments and accept original or certified documents. In‑person verification reduces the risk of mailing irreplaceable originals and can speed fixes if something is missing.

How do you apply for an ITIN step by step?

Apply for an ITIN only if you are not eligible for an SSN and you must be on a U.S. tax return or information form; use Form W‑7 and include required identity and foreign‑status documentation. Refer to the IRS About Form W‑7 page for the current form and instructions.

Once issued, use your ITIN consistently on returns and information forms until you become eligible for an SSN.

What documents and submission methods does Form W-7 require?

A valid passport proves both identity and foreign status and is the preferred single document; if you lack a passport, you must provide a combination of acceptable documents (for example, national ID plus birth certificate) as listed in the W‑7 instructions. Submission options are mailing to the IRS ITIN Operation, scheduling an IRS TAC appointment, or using a CAA. Avoid mailing irreplaceable originals when in‑person verification is available.

How do you apply for an SSN step by step?

If you’re a U.S. citizen, lawful permanent resident, or a noncitizen authorized to work, apply for an SSN using Form SS‑5 and bring original documents or certified copies; see the SSA Form SS‑5 guidance for details.

Once you receive your SSN, use it for wage reporting, tax filings, and credit reporting; if you previously had an ITIN, notify the IRS to consolidate records.

What documents does Form SS-5 require for noncitizens and new residents?

Typically, bring proof of identity (such as a passport), proof of age (such as a birth certificate, if available), and immigration documents that demonstrate your current lawful status and, if applicable, authorization to work. Ensure names and dates match across documents to avoid record mismatches.

How do you manage, renew, and protect these numbers after you get them?

ITINs can expire if unused, and SSNs should be protected like a high‑risk credential; keep addresses updated with the IRS and SSA, store numbers securely, and share them only when required for tax, employment, banking, or credit purposes. If you receive an SSN after using an ITIN, stop using the ITIN and notify the IRS to merge histories.

Act quickly if you suspect identity issues by monitoring accounts and responding to IRS or SSA notices to limit potential damage and administrative burdens.

When do ITINs expire and how do you renew?

The IRS states that an ITIN will expire if it is not used on a federal tax return for three consecutive tax years; see the IRS ITIN Expiration and Renewal guidance for details. Renew by submitting a Form W‑7 renewal package before filing season; use the same submission options as a first‑time W‑7.

Renewing early helps avoid return delays and credit rejections tied to expired ITINs.

How can you tell you used the correct number and everything is in good order?

You’ll know you chose and used the right number if your return is accepted, withholding reconciles, and forms filed by employers or payers match your identifiers; lack of IRS CP notices about TIN mismatches or dependent SSN issues is another good sign.

If a return is rejected for a TIN mismatch, verify the name spelling, date of birth, and the exact number on your SSA card or IRS letter, then correct and resubmit.

What indicators show compliance and fewer rejections?

Smooth filing, no identity or dependency notices, and successful employer/payer validations indicate your records align. When payroll, banks, and the IRS all match your name and number, credits compute properly and refunds arrive without hold‑ups. Respond promptly to any IRS notice about mismatches to avoid cascading issues.

What mistakes should you avoid with ITINs and SSNs?

Avoid common errors that cause rejections, lost benefits, or processing delays: don’t apply for an ITIN if you’re SSN‑eligible; don’t use an ITIN on payroll forms; don’t mail irreplaceable originals when in‑person verification is available; and notify the IRS after obtaining an SSN so records aren’t split.

Check names and dates against your SSA card or IRS records before submitting to reduce corrective work later.

How do misconceptions lead to penalties or delays?

Using an ITIN for employment forms can create payroll and tax mismatches that trigger notices and penalties. Missing SSNs for credits like EITC or CTC can reduce refunds or trigger adjustments, and expired ITINs can hold up processing until renewed. Not consolidating your ITIN history after obtaining an SSN can fragment transcripts and complicate verifications for mortgages, financial aid, or immigration filings.

What should you do next?

Decide based on eligibility: get an SSN through the SSA if you qualify; otherwise, apply for an ITIN through the IRS to meet tax responsibilities. Start with the IRS ITIN page and the SSA Number & Card guidance to prepare documents and apply.

If you need in‑person help, schedule an appointment at an IRS Taxpayer Assistance Center or work with a Certified Acceptance Agent. If you’re opening a bank account with an ITIN, review the CFPB’s guidance on alternatives banks may accept. When you receive an SSN after previously using an ITIN, follow IRS instructions to merge records and use the SSN going forward.

For official forms and instructions, refer to the IRS About Form W‑7, the SSA Form SS‑5, the IRS ITIN Expiration and Renewal page, the IRS Acceptance Agent Program directory, and the SSA Number & Card guidance.