What is a TIN?

A TIN (Taxpayer Identification Number) is issued by the IRS or Social Security Administration to identify individuals and entities for tax purposes. There are several types — and which one you need depends on who you are.

International students on F-1, J-1, or other visa types who earn US-source income — scholarships, fellowships, stipends, or part-time work — must obtain an ITIN if they do not qualify for a Social Security Number.

Who needs an ITIN as a student?

You need an ITIN if you are a non-resident alien who receives taxable US income (grants, research assistantships, tuition waivers counted as income) but are not eligible to work or receive an SSN.

Step-by-step: How to get a student ITIN

1. Confirm SSN eligibility first. If your visa authorizes US employment (e.g. CPT/OPT on F-1), apply for an SSN at the Social Security Administration — an SSN replaces the need for an ITIN.
2. Complete IRS Form W-7. Download it free at irs.gov. Fill in your name, foreign address, date of birth, country of citizenship, and reason for applying (usually “Exception” for students with no return to file yet, or attach your tax return).
3. Gather supporting documents. You need proof of foreign status AND identity. Accepted documents include a valid passport (best — it covers both), national ID card, foreign driver’s license, or birth certificate + photo ID. Originals or certified copies only.
4. Attach your federal tax return (Form 1040-NR) unless you qualify for an exception (e.g. third-party withholding on scholarships). Your university’s international student office can advise which exception code applies.
5. Submit your application. Three options: (a) Mail to IRS Austin, TX 78701; (b) Visit an IRS Taxpayer Assistance Center in person; (c) Use a Certifying Acceptance Agent (CAA) — often available at universities — who certifies documents so you don’t mail originals.
6. Wait for your ITIN. Processing takes 7–11 weeks (longer during tax season, January–April). You’ll receive a CP565 notice by mail with your 9-digit ITIN beginning with the number 9.

Part 2: Business TIN Number (EIN)

Every US business entity — LLC, corporation, partnership, sole proprietorship with employees, or nonprofit — needs an Employer Identification Number (EIN). It’s the business equivalent of a Social Security Number, used for filing taxes, opening a business bank account, hiring employees, and applying for licenses.

Who needs an EIN?

You must get an EIN if your business: has employees, operates as a corporation or partnership, files excise or alcohol/tobacco/firearms taxes, withholds taxes on non-resident alien income, or has a Keogh plan. Sole proprietors without employees may use their SSN instead — but an EIN is still recommended for privacy and professionalism.

Step-by-step: How to get a business EIN

1. Determine your entity type. Know whether you’re a sole proprietor, single-member LLC, multi-member LLC, S-corp, C-corp, partnership, or nonprofit before applying — the form asks this upfront.
2. Identify your responsible party. The IRS requires a “responsible party” — a real individual (not the business entity itself) who controls or manages the entity. You’ll need their SSN or ITIN.
3. Apply online via IRS EIN Assistant (fastest). Go to irs.gov → Businesses → Apply for an EIN Online. The free online tool is available Monday–Friday, 7am–10pm ET. You receive your EIN immediately upon completion.
4. Alternatively, apply by fax. Complete Form SS-4 and fax to the IRS (fax number depends on your state — listed in the SS-4 instructions). You receive your EIN within 4 business days.
5. Or apply by mail. Mail your completed SS-4 to the IRS address for your state. Allow 4–5 weeks for processing. This is the slowest method — avoid unless you have no other option.
6. International applicants without a US SSN must apply by phone: call the IRS Business & Specialty Tax Line at 1-800-829-4933 (available Mon–Fri, 7am–7pm ET). An agent will verify your identity and issue the EIN immediately.
7. Record and protect your EIN. You’ll receive an EIN Confirmation Letter (CP575). Keep it safe — the IRS only issues this letter once. Your EIN is permanent and does not expire.

Quick comparison: Student ITIN vs Business EIN

Frequently asked questions (TIN Number in the USA)