ITIN vs SSN: What's the Difference?
An SSN is a Social Security number the Social Security Administration issues to U.S. citizens and noncitizens authorized to work, and it can authorize employment and Social Security benefits. An ITIN is a 9-digit IRS number (format 9XX-XX-XXXX) for people who must file U.S. taxes but are not eligible for an SSN - it authorizes tax filing only, never work or benefits. Both are free from the government.
Quick Answer
- Choose an SSN if
- You are a citizen or a noncitizen authorized by DHS to work - you are eligible for one
- Use an ITIN if
- You have a U.S. tax filing need but cannot get an SSN
- Who issues
- SSN: Social Security Administration · ITIN: Internal Revenue Service
- Apply with
- SSN: Form SS-5 · ITIN: Form W-7
- Authorizes work?
- SSN: yes (if work-eligible) · ITIN: no
- Cost
- $0 for either
ITIN vs. SSN at a Glance
An ITIN and an SSN are both nine-digit U.S. taxpayer identifying numbers, but they come from different agencies, serve different purposes, and reach different people. The table sets them side by side.
| Feature | ITIN | SSN |
|---|---|---|
| Full name | Individual Taxpayer Identification Number | Social Security number |
| Issued by | Internal Revenue Service (IRS) | Social Security Administration (SSA) |
| Who is eligible | People with a federal tax purpose who cannot get an SSN | Citizens and noncitizens authorized to work by DHS |
| Format | 9XX-XX-XXXX (always begins with 9) | NNN-NN-NNNN |
| Application form | Form W-7 | Form SS-5 |
| Authorizes work? | No | Yes, if the SSN is valid for employment |
| Social Security benefits? | No | Yes - earnings build benefit eligibility |
| Earned Income Tax Credit? | No | Yes, with a valid work-eligible SSN |
| Cost | $0 | $0 |
Who Issues Each Number
The issuing agency is the first fork. The Social Security Administration issues the Social Security number and card, using Form SS-5, the Application for a Social Security Card. The IRS issues the ITIN, using Form W-7. That split matters because each agency controls who qualifies: the SSA is bound by immigration and work-authorization rules, while the IRS grants ITINs regardless of immigration status, purely to enable tax compliance. As the IRS explains on its Taxpayer Identification Numbers page, an ITIN is "a tax processing number only available for certain nonresident and resident aliens, their spouses, and dependents who cannot get a Social Security Number."
The two application paths look different in practice. To get an SSN, a work-authorized applicant generally schedules an appointment with the SSA - the agency's phone line is 1-800-772-1213 - and presents evidence of identity, age, and work authorization. To get an ITIN, the applicant files Form W-7 with the IRS and, in most cases, attaches the federal tax return that creates the filing need. One number is administered as part of the Social Security program; the other lives entirely inside the federal tax system. That is why an SSN can feed your earnings record while an ITIN cannot: the SSA, not the IRS, tracks wages toward benefits.
Who Is Eligible for Each
Eligibility is nearly mutually exclusive. You qualify for a Social Security number if you are a U.S. citizen or a noncitizen whom the Department of Homeland Security has authorized to work; the SSA publication Social Security Numbers for Noncitizens states that, in general, only noncitizens with DHS permission to work can get an SSN. If you are eligible for an SSN, you cannot get an ITIN - the IRS directs you to the SSN instead. Conversely, you qualify for an ITIN only if you have a federal tax purpose and are not eligible for an SSN. That is why the two numbers rarely overlap: the ITIN exists precisely to cover the people the SSN system cannot.
Foreign workers who do gain work authorization can obtain an SSN by showing documents such as an I-94 or an I-766 Employment Authorization Document, per the SSA's guidance for foreign workers. Until then, a person with a U.S. filing obligation uses an ITIN. The SSA also addresses this directly in its FAQ on whether a noncitizen can get a Social Security number: in general, only noncitizens authorized to work by the Department of Homeland Security are assigned one. Someone who is present in the United States but not work-authorized, yet still has a filing or reporting duty, is precisely the person the ITIN was designed for. That is why the eligibility tests almost never overlap - if one number is open to you, the other usually is not.
What Each Number Authorizes
This is the difference that trips people up most. A Social Security number valid for employment lets you work legally in the United States, reports your wages to the SSA, and builds your record toward Social Security retirement and disability benefits. An ITIN does none of that. The IRS is explicit that an ITIN does not authorize work, does not provide or change immigration status, does not qualify you for Social Security benefits, and does not serve as identification outside the federal tax system. Its single job is to put a valid identifying number on a tax return. For the fuller treatment, see what is an ITIN.
The practical consequences follow from that gap. An employer completing Form I-9 and payroll reporting needs a work-eligible SSN, not an ITIN, because the ITIN carries no work authorization. A person filing only to report investment income, a treaty claim, or a dependent's presence on a return needs an identifying number but not work authorization, so the ITIN fits exactly. And because the ITIN never enters the Social Security earnings system, time spent filing under an ITIN does not build any Social Security benefit - only earnings reported under a valid SSN do. Keeping the roles clear avoids the common error of treating the ITIN as a work permit or a substitute for the SSN.
Format: How to Tell Them Apart
An ITIN is written exactly like an SSN - nine digits in the pattern NNN-NN-NNNN - which makes them easy to confuse on paper. The tell is the first digit: an ITIN always begins with the number 9, written as 9XX-XX-XXXX, while an SSN can begin with other digits. Neither should be confused with an Employer Identification Number, which identifies a business and uses a two-digit prefix in the pattern XX-XXXXXXX. Compare all three individual and business IDs in ITIN number and the ITIN glossary entry.
Benefits, Credits, and the EITC
The benefits gap is concrete. To claim the Earned Income Tax Credit, the IRS requires that you, your spouse if filing jointly, and each qualifying child have a valid Social Security number issued on or before the due date of the return, including extensions. An ITIN never satisfies that test, so ITIN filers cannot claim the EITC. An SSN issued solely to receive a federally funded benefit, marked "Not valid for employment," also fails the EITC test. ITIN holders may still qualify for certain other tax benefits depending on their circumstances, but the EITC and Social Security retirement credits require a work-eligible SSN.
When to Get an SSN
Get a Social Security number whenever you are eligible for one - it is the default identifying number for individuals under federal law. Under 26 U.S. Code § 6109, the Social Security account number is the identifying number individuals must use on tax returns "except as shall otherwise be specified under regulations." A U.S. citizen, a lawful permanent resident, or a noncitizen granted work authorization should apply for the SSN because it does everything an ITIN does for tax purposes and also authorizes employment and benefits. To apply, you complete Form SS-5 and present proof of identity, age, and work-authorized status to the SSA.
When to Use an ITIN
Use an ITIN when you have a U.S. tax filing or reporting obligation but the SSN door is closed to you. Common situations include a nonresident alien reporting U.S.-source income, a resident alien who meets the substantial-presence test but is not work-authorized, and a nonresident spouse or dependent a U.S. taxpayer lists on a return. You obtain it by filing Form W-7 with your return and proof of identity and foreign status - the full walkthrough is in how to get an ITIN. Note that an ITIN can also serve as the responsible party's number on a business EIN application; see can you get an EIN without an SSN.
How to Switch from an ITIN to an SSN
If you later become eligible for a Social Security number, you must stop using the ITIN. Apply for the SSN with the SSA, and once it is issued, notify the IRS in writing so it can rescind the ITIN and merge your prior tax records under the new SSN. You do not keep both numbers active. From that point forward, you use only the SSN on returns, and your earlier ITIN-based filing history is consolidated so credits and payments carry over correctly.
This transition is common for people whose immigration or work status changes - for example, a nonresident who becomes a lawful permanent resident, or a visa holder who receives work authorization. After the SSN arrives, use it on the next return and on any updated payroll or banking records. Consolidating the records under the SSN matters because it links your prior ITIN filings to your new number, so the Social Security earnings you begin building are credited correctly and your tax history stays intact. Do not continue filing under the old ITIN once the SSN is issued.
Common Mistakes
The most damaging errors come from treating the two numbers as interchangeable. Filers sometimes present an ITIN to an employer as if it authorized work - it does not, and doing so can create problems. Others claim the EITC with an ITIN, which the IRS will disallow. Some keep using an ITIN after receiving an SSN, splitting their records across two numbers. And many confuse the ITIN's 9-prefix with an SSN or an EIN. Keeping the roles straight - SSN for the eligible, ITIN for everyone else with a tax duty, and an EIN for a business - avoids all four. Founders can start at how to form an LLC.
A final reminder ties the comparison together. Eligibility drives everything: if you can get a Social Security number, get it, because it does everything an ITIN does for tax filing and also authorizes work and builds benefits. If you cannot get an SSN but still owe or must be reported on U.S. tax, the ITIN is the correct - and only - individual number available to you. The two are not competing options you choose between on preference; they are assigned by different agencies to different populations under different rules, and the leading 9 on an ITIN is your quick visual check of which one you are holding.
Frequently Asked Questions
What is the main difference between an ITIN and an SSN?
An SSN is issued by the Social Security Administration to citizens and work-authorized noncitizens and can authorize employment and benefits. An ITIN is issued by the IRS only for federal tax filing to people not eligible for an SSN, and authorizes neither work nor benefits.
Can I have both an ITIN and an SSN?
No. You use one or the other. If you become eligible for an SSN, stop using the ITIN, notify the IRS, and use the SSN so the IRS can merge your prior tax records under it.
Can I work with an ITIN instead of an SSN?
No. The IRS states an ITIN does not authorize work. Only a Social Security number issued to a citizen or a DHS-authorized worker permits employment in the United States.
Can I claim the Earned Income Tax Credit with an ITIN?
No. The IRS requires a valid SSN for the taxpayer, spouse if filing jointly, and any qualifying child to claim the EITC. An ITIN cannot be used.
Do an ITIN and an SSN look the same?
They share the format NNN-NN-NNNN, but an ITIN always begins with 9, as 9XX-XX-XXXX. An SSN can begin with other digits, and an EIN uses a two-digit prefix.
How much does each number cost?
Both are free. The IRS charges no fee for Form W-7 for an ITIN, and the SSA charges no fee for Form SS-5 for an SSN and card.
Related Guides
- What is an ITIN? - the full definition and legal basis.
- ITIN number - format 9XX-XX-XXXX and quick overview.
- How to get an ITIN - the step-by-step Form W-7 process.
- ITIN renewal - how to renew an expired ITIN.
- Can you get an EIN without an SSN? - using an ITIN as responsible party.
- How to get an EIN - the business tax ID process.
- ITIN (glossary) - the one-line definition.
- How to form an LLC - the formation hub tying these IDs together.
Sources
- IRS - Individual Taxpayer Identification Number (ITIN definition, issued regardless of status, what it does not do).
- IRS - Taxpayer Identification Numbers (TIN) (SSA issues SSN, ITIN begins with 9, ITIN is a tax processing number, no EITC).
- IRS - About Form W-7 (ITIN application form).
- IRS - Who qualifies for the EITC (valid SSN required for taxpayer, spouse, and child).
- IRS - About Form SS-4 (EIN for a business, two-digit prefix context).
- SSA - Form SS-5, Application for a Social Security Card (SSA issues SSNs; no fee).
- SSA - Social Security Numbers for Noncitizens (only DHS-work-authorized noncitizens may get an SSN).
- SSA - Foreign Workers and Social Security Numbers (I-94 / I-766 evidence of work authorization).
- SSA - If I am not a U.S. citizen, can I get a Social Security number? (noncitizen SSN eligibility).
- IRS - How to apply for an ITIN (submission methods for Form W-7).
- IRS - How to renew an ITIN (three-year non-use expiration rule).
- Cornell Legal Information Institute - 26 U.S. Code § 6109, Identifying numbers (SSN as default individual identifier; § 6109(i) ITIN provisions).
LegalGlass provides general information for educational purposes and is not a law firm or a substitute for advice from a licensed attorney or tax professional. This page is information, not advice. Laws, forms, and eligibility rules change; verify current requirements with the IRS and the Social Security Administration before acting.