How do ITINs differ from Social Security numbers for noncitizens?
Executive summary
ITINs are tax-only nine-digit numbers issued by the IRS to people who must file U.S. tax returns but “do not have and can’t get” an SSN; they begin with 9 and do not authorize work or Social Security benefits (IRS; expat guides) [1] [2]. SSNs are issued by the Social Security Administration to U.S. citizens, lawful permanent residents and noncitizens authorized to work — they enable employment reporting, benefit eligibility and broader ID uses (SSA/expert summaries) [3] [4].
1. What the two numbers are and who issues them — two separate federal systems
The SSN is a Social Security Administration identifier tied to earnings records and benefit eligibility; it is the standard taxpayer ID for most people [3] [4]. The ITIN is a tax processing number created and issued by the IRS for people who need to file U.S. tax returns but “do not have and can’t get an SSN” — it exists solely so the IRS can process tax returns and refunds [1] [5].
2. Eligibility and purpose — work authorization is the dividing line
An SSN is granted to those entitled to work in the U.S.: U.S. citizens, green card holders and noncitizens with work authorization from DHS; it is the primary TIN for tax filings when available [3] [4]. An ITIN is for noncitizens (resident or nonresident) who aren’t eligible for an SSN but need a taxpayer identification number to file or be listed on federal tax returns [5] [1].
3. What each number allows you to do — benefits, employment and ID uses
An SSN enables employers to report wages and withhold Social Security/Medicare, and it is the key number tied to retirement, disability and survivor benefits after sufficient work credits are earned [3]. An ITIN does not entitle holders to Social Security benefits, does not authorize employment, and is intended strictly for tax filing; it “creates no inference” about immigration status or work authorization but does not confer those rights [1] [2].
4. Practical effects for families, credits and tax benefits
The presence or absence of an SSN affects eligibility for certain tax credits and how they are claimed. Lawmakers and CRS analysis note that policy changes have required work-authorized SSNs for some child tax credit claims (a requirement tied to work-authorized SSNs through 2025, with rules possibly reverting in 2026 unless Congress acts) — illustrating how SSN status can alter access to benefits even where ITINs permit filing [6]. The IRS and practitioners emphasize that ITIN holders can file and claim many tax items, but some credits or program rules depend on having a qualifying SSN [1] [7].
5. Administrative differences: applications, expirations and record merging
SSNs are applied for through SSA procedures (Form SS-5 and verification of authorization) and, since 2025 updates, involve stronger identity-proofing and sometimes digital verification [2] [8]. ITINs are applied via IRS Form W‑7 and expire after periods of non-use; IRS guidance and tax advisers note ITINs that go unused for three consecutive years expire and must be renewed [1] [9]. If an ITIN holder later becomes eligible for an SSN, the IRS will merge tax records under the new SSN after notification [8] [2].
6. Risks, privacy and policy tensions — competing viewpoints in the sources
Legal and advocacy sources warn about potential risks from data sharing between tax and immigration authorities: some sources reported litigation and temporary halts to data sharing arrangements in 2025, reflecting conflicting government priorities between tax administration and immigration enforcement [3]. Proponents of ITINs stress they enable tax compliance for people without SSNs; critics and some lawmakers have sought to limit benefit access tied to SSNs as a way to restrict program use by those without work authorization [5] [6].
7. Bottom line for noncitizens deciding which number applies to them
If you’re authorized to work in the U.S., you should apply for an SSN — it is the standard TIN and it opens employment and benefit pathways [4] [8]. If you must file a U.S. tax return but cannot get an SSN, you must use an ITIN; it allows tax compliance but not employment authorization or Social Security benefits, and it can expire if unused [1] [9].
Limitations and sources: This analysis relies only on IRS guidance, congressional research and recent practitioner articles provided by the user; state-level variations, bank or driver‑license practices, and evolving litigation over data sharing are noted in some sources but detailed local rules are not covered here [1] [3] [5].