1) Download IRS Form W-7:https://www.irs.gov/pub/irs-pdf/fw7.pdfCost: Free — the IRS does not charge a filing fee.
2) Gather Required Supporting Documents:● Original or certified copies of your passport or two alternate IDs proving identity and foreign status.●  Your federal tax return (Form 1040, 1040-NR, or 1040-SR) — unless you qualify under an exception. ● A completed W-7 form with all required fields filled accurately and legibly. ● If applicable, include a U.S. visa, scholarship letter, or tax treaty statement. 
3) Complete Form W-7 Carefully: ● Enter your full legal name as shown on your passport.●  Use a valid foreign address (if applicable) and U.S. mailing address for correspondence. ● Select the correct reason for applying (e.g., “Nonresident alien required to obtain ITIN to claim tax treaty benefit”). ● Include your date of entry to the U.S. if you’ve been physically present. 
4) Submit Your Application to the IRS:Choose one of three methods:By Mail:Send your completed Form W-7, tax return, and original/certified documents to:Internal Revenue ServiceITIN OperationP.O. Box 149342Austin, TX 78714-9342 USAProcessing time: 6–8 weeks.Cost: Free (postage and notarization costs may apply).
In Person (U.S. Only):Apply through an IRS-authorized Certified Acceptance Agent (CAA) or Taxpayer Assistance Center (TAC).Find one near you:https://www.irs.gov/help/contact-my-local-office-internationallyCost: Varies by location (typically $50–$150 for certification).
Through a CAA Abroad:Non-U.S. residents can submit documents through a foreign-based Certified Acceptance Agent to avoid mailing passports.Cost: Varies. Typically $100–$250 depending on the provider. 
5) Receive Your ITIN: If approved, the IRS will mail your ITIN assignment letter (Form CP 565) to your provided U.S. mailing address. Processing usually takes 6–8 weeks (faster with CAA assistance).