Background and purpose

Taxpayer Identification Numbers (TINs) let the IRS match income, credits and payments to the correct taxpayer. The most familiar TIN is the Social Security number (SSN). Other TINs include the Employer Identification Number (EIN), Individual Taxpayer Identification Number (ITIN), Adoption Taxpayer Identification Number (ATIN) and Preparer Taxpayer Identification Number (PTIN). ITINs were created so people who aren’t eligible for SSNs can meet filing and withholding obligations under U.S. tax law (IRS: Taxpayer Identification Numbers (TINs)).

In my work advising clients, I’ve seen ITINs prevent costly late filings and penalties when non‑eligible SSN filers follow the Form W‑7 process to become compliant. They’re identification tools—not immigration documents or work-authorizations.

How TINs and ITINs work

  • SSN: issued by Social Security Administration for U.S. citizens, permanent residents and certain work-authorized noncitizens.
  • EIN: issued to businesses, estates and trusts for tax reporting.
  • ITIN: issued by the IRS to individuals who need a U.S. taxpayer ID but aren’t eligible for an SSN; obtained using Form W‑7.
  • ATIN: temporary number for children in adoption cases.
  • PTIN: for paid federal tax return preparers.

To apply for an ITIN you generally submit Form W‑7 with your federal tax return (or meet an exception) and provide original or certified copies of identity and foreign status documents (commonly a passport) (IRS: ITIN Information).

Real-world examples

  • Nonresident foreign investors: use ITINs to report U.S. rental income or capital gains.
  • Spouses or dependents who can’t get an SSN: file returns and claim credits using ITINs when eligible.
  • Expatriates with U.S. filing obligations but no SSN: obtain ITINs to remain compliant and avoid penalties.

Who is affected and who is eligible

  • Individuals required to file a U.S. tax return but ineligible for an SSN.
  • Dependents or spouses claimed on a U.S. tax return who aren’t eligible for an SSN.
  • Businesses don’t use ITINs for hiring—employees who can work must have SSNs or appropriate work authorization; businesses use EINs for employer reporting.

Eligibility typically requires a filing requirement or a qualifying exception and supporting identification documents submitted with Form W‑7 (IRS: Form W‑7 instructions).

Practical tips and strategies

  1. Gather certified documents before applying: a passport alone is usually sufficient; otherwise collect two or more ID documents. Using certified copies from the issuing agency speeds the process. (IRS: ITIN documentation).
  2. File early: submit Form W‑7 and the tax return as early as possible — processing can add weeks. If you need proof of filing for visas or banking, keep all IRS receipts.
  3. Use an IRS‑authorized Certified Acceptance Agent (CAA) or a reputable tax professional for complex cases; CAAs can verify documents so you don’t have to mail originals.

Common mistakes and misconceptions

  • ITINs are not SSNs: ITINs do not authorize work in the U.S. and do not change immigration status.
  • Expiration rules: ITINs can expire. ITINs not used on a federal tax return for three consecutive years may expire; the IRS also required renewal of certain ITINs issued before 2013 — check current IRS guidance before relying on an old ITIN. (IRS: ITIN renewal guidance)
  • Banking and credit: some financial institutions accept ITINs for accounts, but acceptance varies — an ITIN does not automatically give access to credit or employment.

Short FAQs

Q: How long does it take to get an ITIN?
A: Processing times vary; the IRS typically advises several weeks. Using a CAA can avoid mailing originals and may shorten turnaround. See Form W‑7 instructions for current timing (IRS Form W‑7).

Q: Can I use an ITIN to get a mortgage or other loan?
A: Some lenders accept ITINs for loan applications and for opening accounts, but underwriting rules differ by lender and product. Check with lenders early—see related guides on what documentation lenders request and how they evaluate liquidity when applying for loans (what documents lenders want, how lenders evaluate liquidity).

How to apply (quick checklist)

  • Determine if you need a TIN and which type.
  • Complete Form W‑7 if seeking an ITIN; attach a completed federal tax return unless you qualify for an exception.
  • Provide original or certified copies of identity/foreign status documents or use a CAA.
  • Mail to the IRS or submit through an acceptance agent; keep copies of everything.

Professional disclaimer

This article provides general information and educational context, not personalized tax advice. For advice tailored to your situation, consult a qualified tax professional or contact the IRS directly.

Authoritative sources

Internal resources

If you’d like a checklist or sample Form W‑7 packet for common scenarios, consult a tax pro or visit the IRS pages above.