ITIN Application: Complete Guide for 2026

What Is an ITIN Application and Who Files One in 2026?

The ITIN application is the official process for requesting an Individual Taxpayer Identification Number from the Internal Revenue Service. The IRS created the program in 1996 to give non-residents, their spouses, and dependents a way to comply with US tax law when they cannot qualify for a Social Security Number. The legal basis is 26 U.S.C. Section 6109, which requires every person filing a US tax return to include an identifying number.

7 categories of filers commonly need an ITIN application. Each category requires the same Form W-7, but the documentation and attachments differ.

• Non-resident aliens with US-source income filing Form 1040-NR.
• Resident aliens meeting the substantial presence test but ineligible for an SSN.
• Spouses of US citizens or resident aliens filing jointly.
• Dependents of US citizens or resident aliens listed on a return.
• Foreign students, professors, and researchers on F, J, M, or Q visas claiming a treaty exemption.
• Foreign investors with US dividends, royalties, or rental income subject to withholding.
• Foreign LLC owners required to file Form 5472 with a pro forma 1120.

See the companion definition page on what an ITIN is for the underlying number itself and the full ITIN definition.

What Are the Requirements for an ITIN Application?

Every ITIN application packet must contain 3 components: a completed Form W-7, a federal tax return (with exceptions), and supporting identity and foreign-status documents. Missing any one component triggers an automatic rejection notice (CP566) from the IRS.

Form W-7 Application

Form W-7 is a 2-page IRS form revised most recently in October 2024. It collects the applicant's legal name, mailing address, country of citizenship, foreign tax ID (if any), US visa information, and reason for applying (lines 6a through 6h). The reason code on line 6 is the most-error-prone field on the form. Read the full Form W-7 Instructions line-by-line walkthrough.

Attached Federal Tax Return

Most applicants must attach Form 1040 or 1040-NR with the ITIN application. The return is filed without an SSN/ITIN number in the taxpayer field; the IRS assigns the ITIN and posts the return simultaneously. Applicants who qualify under 1 of the 5 IRS exceptions can file Form W-7 without an attached return.

Identity and Foreign-Status Documents

The IRS publishes 13 acceptable documents in IRS Publication 1915. A current passport is the only standalone document; it proves both identity and foreign status. Without a passport, the applicant must submit 2 documents: one proving identity, one proving foreign status. Acceptable IDs include national identity card, foreign driver's license, civil birth certificate, US visa, USCIS photo ID, and foreign military ID.

How Does the ITIN Application Process Work, Step by Step?

The end-to-end ITIN application has 5 stages. Each stage has specific timing and documentation requirements.

1. Determine eligibility. Confirm SSN ineligibility and identify which Form W-7 reason code applies (6a through 6h). Applicants who qualify for an SSN must apply for one instead; filing a W-7 in that case results in rejection.
2. Complete Form W-7. Use black ink or type the form electronically. Include the foreign tax ID if assigned, the US visa number if held, and the exact name as it appears on the passport. Unsigned forms are auto-rejected.
3. Prepare the federal tax return. Most applicants file Form 1040 or 1040-NR. Leave the taxpayer SSN/ITIN field blank; the IRS populates it after assignment. Sign and date the return.
4. Gather identity documents. Originals or certified copies issued by the document originator. Notarized copies are not accepted as of 2026.
5. Submit the packet. Choose between 3 submission channels: a Certifying Acceptance Agent, mail to the IRS, or an in-person visit to an IRS Taxpayer Assistance Center.

For the full procedural breakdown with timing and forms, see the step-by-step guide on how to get an ITIN.

What Are the 3 Ways to Submit an ITIN Application?

The IRS accepts ITIN applications through 3 distinct channels. Each has a different document-handling rule, turnaround time, and risk profile.

Working through a Certifying Acceptance Agent is the preferred route for applicants outside the United States because the passport never leaves the holder.

How Long Does an ITIN Application Take to Process?

The IRS publishes 7 weeks as standard, but 2025-2026 data shows actual processing averages 7 to 11 weeks. Peak filing season (January through April) routinely runs 11+ weeks because the ITIN Operation center prioritizes returns due that filing year.

• Off-peak (May-November): 7-9 weeks from IRS receipt to CP565 notice.
• Peak season (January-April): 9-11+ weeks. Mailed applications often go silent for 8 weeks before status updates.
• International mail: Add 1-3 weeks transit each way, plus 60-65 days for original-document return.
• Rejected applications: CP566 notice arrives 6-10 weeks after submission; refiling restarts the timeline.

Live status thresholds and call-center timing details live on the ITIN processing time guide.

What Are the Most Common Reasons an ITIN Application Is Rejected?

The IRS rejects approximately 25% of mailed ITIN applications. The 6 leading rejection causes are administrative, not substantive, which means almost every rejection is preventable.

1. Missing or mismatched signature on Form W-7. Spouses and dependents over age 18 must sign their own forms.
2. Uncertified document copies.Photocopies, scans, and notarized copies are not accepted; certification must come from the document's original issuing authority.
3. Incorrect reason for applying (line 6). Selecting the wrong reason code causes the IRS to reject for missing supporting documentation.
4. Tax return missing or filed separately. Form 1040 must be inside the same envelope unless an exception applies.
5. Passport quality issues. Expired passports, passports without the photo page, or pages missing the signature page.
6. Name or date-of-birth mismatch. Differences between Form W-7 and supporting documents trigger automatic rejection.

The full diagnostic walkthrough lives on the ITIN rejection guide.

How Much Does an ITIN Application Cost in 2026?

The IRS charges $0 to process Form W-7. Indirect costs arise from document certification, secure international shipping of original documents, and the optional use of a Certifying Acceptance Agent.

See the ITIN cost guide for line-by-line pricing across service tiers.

What Happens After the ITIN Application Is Approved?

The IRS mails a CP565 notice confirming the assigned ITIN, usually 7 to 10 days after the number is generated. The CP565 is the official record. Banks, lenders, employers, and state agencies all accept the CP565 as proof of ITIN issuance. No plastic ITIN card exists.

• Tax return processing. The attached Form 1040 moves into IRS processing once the ITIN is assigned. Refunds, if any, ship within 6 weeks of return acceptance.
• Document return. Original passports and IDs are mailed back within 60 to 65 days of the IRS receipt date.
• 3-year usage rule. The ITIN remains active as long as it is used on a federal return at least once every 3 consecutive years.

CP565 details and what to do if the notice is lost live on the CP565 notice page.

How Is an ITIN Application Different From an ITIN Renewal?

A new ITIN application requests an unissued number. An ITIN renewal reactivates a previously issued ITIN that expired through 3 consecutive years of non-use or under the IRS rolling expiration program (middle digits 70-88).

• Both use the same Form W-7; renewals check the “Renew an existing ITIN” box.
• Renewals do not require an attached tax return when filed standalone.
• Family-pack renewals are permitted: spouse and dependent ITINs renew together to align expiration cycles.

Complete renewal mechanics, eligibility, and timing live on the ITIN renewal page.