IRS Publication 4520 – IRS Forms, Instructions, Pubs 2026

IRS Publication 4520 – IRS Forms, Instructions, Pubs 2026 – Individual Taxpayer Identification Numbers (ITINs) help millions of non-U.S. citizens and residents meet federal tax obligations. IRS Publication 4520 serves as the official handbook for professionals who assist these individuals: Acceptance Agents (AAs) and Certifying Acceptance Agents (CAAs).

Revised in January 2025 (Rev. 1-2025), this guide details procedures, documentation, responsibilities, and compliance rules for helping applicants obtain or renew ITINs via Form W-7. Whether you are a tax professional, attorney, financial institution, or organization considering the Acceptance Agent program—or an individual seeking ITIN assistance—this article breaks down Publication 4520 with the latest IRS guidance.

What Is an ITIN and Why Does Publication 4520 Matter?

An ITIN is a nine-digit tax processing number issued by the IRS for individuals who must file U.S. tax returns but do not qualify for (or cannot obtain) a Social Security Number (SSN). It applies to foreign nationals, dependents, spouses of U.S. citizens or residents, and others with U.S. tax obligations, such as reporting income, claiming treaty benefits, or filing returns for real estate transactions.

Publication 4520 (full title: Acceptance Agents’ Guide for Individual Taxpayer Identification Number) explains how authorized agents streamline the ITIN application process. It covers:

Application requirements
Document authentication
Submission procedures
Recordkeeping
Compliance

The IRS publishes the guide to ensure accuracy and efficiency, reducing processing delays and errors. Download the latest PDF directly from the IRS: Publication 4520 (Rev. 1-2025).

ITINs differ from SSNs (for employment) and EINs (for businesses). They are for tax purposes only.

Acceptance Agents vs. Certifying Acceptance Agents (AA vs. CAA)

The IRS authorizes two types of agents under Revenue Procedure 2006-10. Both help complete Form W-7, but their authority and responsibilities differ.

Feature	Acceptance Agent (AA)	Certifying Acceptance Agent (CAA)
Document Review	Reviews originals/certified copies	Authenticates most documents (except foreign military IDs and certain dependent docs)
Submission	Forwards Form W-7 + originals to IRS	Submits Form W-7 + Certificate of Accuracy (Form W-7 COA) + copies
Document Return	IRS returns originals	Returns authenticated documents to applicant immediately
ITIN Receipt	IRS sends to applicant only	Receives copy of ITIN notices directly
Training Requirements	ITIN Acceptance Agent Training	ITIN Training + Forensic Document Identification Training
Best For	Basic assistance	High-volume practices, real estate closings, international clients

CAAs offer faster service for clients because they authenticate documents upfront. Many large firms (e.g., Deloitte, EY, KPMG, PwC) participate as CAAs.

How to Become an ITIN Acceptance Agent or CAA in 2026?

The IRS modernized the program with a fully electronic application process. No more paper Form 13551.

Step-by-Step Process (updated for 2025–2026):

Complete Mandatory Training (before applying)
- All responsible parties (RPs) must finish the ITIN Acceptance Agent Training (Publication 5726, Rev. 3-2025).
- CAAs only: Complete free Forensic Document Identification Training.
- No certification statement is required—just acknowledge completion in the application.
Register for IRS e-Services and submit the electronic Acceptance Agent Application.
- Designate roles: Principal/Partner/Owner (PPO), Principal Consent, Responsible Parties, and Contacts.
- Upload supporting documents (e.g., credentials, training proofs) via the CAA Documentation Upload Tool after submission.
IRS Review — Properly submitted applications process in about 60 days (allow up to 75 days due to occasional backlogs).
Execute Agreement — Sign the Acceptance Agent Agreement upon approval.

Key Requirements:

Valid EIN for the business/organization
Responsible parties must have SSN or ITIN (exceptions for certain foreign entities)
Pass tax compliance and suitability checks
Maintain records and cooperate with IRS compliance reviews

No IRS fee applies, but agents may charge clients for services. Find full details and start your application at the ITIN Acceptance Agent Program page.

The ITIN Application Process Through an Acceptance Agent

Publication 4520 provides a detailed checklist (Exhibit K) for error-free submissions.

Core Requirements:

Form W-7 (Rev. December 2024) — Check “new” or “renew” and select a reason (a–h).
U.S. federal tax return (unless claiming an exception).
Supporting documentation proving identity and foreign status.

Submission Address:

Mail to: Internal Revenue Service, ITIN Operations, P.O. Box 149342, Austin, TX 78714-9342
Overnight: Mail Stop 6090-AUSC, 3651 S. Interregional Hwy 35, Austin, TX 78741-0000

CAAs attach Form W-7 COA and retain copies of documents.

Processing Time: Typically 7 weeks (up to 11 weeks during peak season). New ITINs cannot be used for e-filing in the same calendar year.

Example of Form W-7 – the starting point for every ITIN application.

Acceptable Supporting Documentation (Exhibit A in Pub 4520)

Documents must be original or certified copies, current, and from the IRS-approved list. A passport is the only standalone document proving both identity and foreign status.

Common Combinations:

Passport (with U.S. entry date for most dependents)
National ID card (with photo, address, DOB, expiration)
Visa + foreign driver’s license
For dependents under 18 (or 24 if students): Birth certificate + school/medical records

Important Rules:

At least one photo ID for applicants over 14 (18 if full-time students).
Foreign documents need certified English translations if not in English.
CAAs cannot authenticate foreign military IDs.

Full table and exceptions appear in Publication 4520, Part 4.

Exceptions to Filing a Tax Return (No Return Required)

Applicants may qualify for an ITIN without attaching a tax return under specific “exceptions” (detailed in Pub 4520, Exhibit C):

Exception 1: Third-party withholding on passive income (e.g., partnerships, pensions)
Exception 2: Wages, scholarships, gambling winnings (often with treaty benefits or SEVP certification for students)
Exception 3: Mortgage interest (Form 1098 reporting)
Exception 4: Sale of U.S. real property (FIRPTA withholding)
Exception 5: Treasury Decision 9363 compliance (employer letter required)

These exceptions are common for real estate investors, students, and foreign sellers.

Recordkeeping, Compliance, and Common Pitfalls

CAAs and AAs must:

Retain copies of all Forms W-7, documents, tax returns, and IRS notices.
Conduct in-person (or video) interviews.
Report changes in business structure or responsible parties promptly.

Infractions range from warnings (minor) to termination (flagrant, e.g., using expired documents).

Common Errors to Avoid:

Name/address mismatches between Form W-7 and documents
Missing entry dates on passports for dependents
Submitting incomplete exception documentation
Using non-approved documents

Recent Updates (2025–2026)

Fully electronic applications (paper eliminated)
Updated training materials (2025 revisions)
Processing resumed after 2025 government shutdown (up to 75-day backlog clearance)
Emphasis on allowable tax benefits for spouses/dependents (post-2017 rules)
New Form W-7 COA revisions (Rev. 8-2025)

The IRS maintains a public list of approved agents by state and country—searchable on IRS.gov.

Resources and Next Steps

Official IRS Links:

Contact:

ITIN Policy Section: [email protected]
General IRS: 1-800-829-1040 (U.S.) or 267-941-1000 (international)

Ready to Act?

Tax professionals: Complete training and apply to become an AA or CAA—expand your services and help international clients.
Individuals needing an ITIN: Use the IRS agent locator or work with a trusted CAA for faster processing and document return.

IRS Publication 4520 remains the definitive resource for compliant, efficient ITIN assistance. Bookmark this page and the official PDF for the most current procedures as tax season approaches.

Last updated: February 2026. Always verify the latest forms and guidance directly on IRS.gov, as rules can evolve.