What Is a GIIN Number? FATCA Rules and Who Needs One

A Global Intermediary Identification Number, or GIIN, is a 19-character code the IRS assigns to a foreign financial institution or certain other foreign entity that has registered under the Foreign Account Tax Compliance Act (FATCA). The number serves as proof that the entity has agreed to identify and report accounts held by US taxpayers. Without a valid GIIN listed by the IRS, a foreign financial institution generally has 30% withheld from US-source payments such as dividends, interest, and certain sale proceeds.¹

What the GIIN Actually Does

FATCA requires foreign financial institutions worldwide to report information about accounts held by US taxpayers to the IRS. Entities that fail to register face a flat 30% withholding tax on covered US-source payments.² The GIIN is how a US paying bank or broker knows whether the foreign entity on the other end of a transaction has signed up.

When a US withholding agent sends a payment to a foreign financial institution, the agent checks the institution’s GIIN against the IRS FFI List, a publicly searchable database of all registered entities.³ If the GIIN matches, the payment goes through clean. If the institution isn’t on the list, the agent must take 30% off the top and send it to the US Treasury.

The foreign institution supplies its GIIN on IRS Form W-8BEN-E, the standard tax certification foreign entities use when receiving US-source income. That form, combined with FFI List verification, gives the withholding agent reasonable assurance that the recipient is meeting FATCA’s due diligence and reporting obligations.

The 30% withholding does not apply to every dollar crossing a border. It targets specific categories of US-source income: interest, dividends, rents, salaries, wages, annuities, and other recurring income from US sources, along with gross proceeds from selling property that could generate US-source interest or dividends, such as stock in US companies.⁴ Income effectively connected with a US trade or business is excluded, since it is already taxed through a different mechanism.

Reading the 19 Characters

The GIIN follows a standardized format, XXXXXX.XXXXX.XX.XXX, with four segments separated by periods. Each segment encodes specific information about the registered entity.⁵

Characters 1–6 are the FATCA ID, a randomly generated alphanumeric code unique to the institution. The letter “O” is never used, to avoid confusion with zero.
Characters 8–12 identify the entity’s role in its corporate group. A standalone institution shows “99999,” a lead entity of an affiliated group shows “00000,” and members receive sequential numbers starting at “00001.”
Characters 14–15 are the category code: “LE” for a lead entity, “SL” for a single (standalone) entity, “ME” for a member, “BR” for a branch, and “SP” for a sponsoring entity.
Characters 17–19 are the ISO 3166-1 numeric country code for the jurisdiction where the institution or branch is located.

A withholding agent can glance at a GIIN and tell whether the counterparty is a standalone bank in one country or a branch of a larger affiliated group in another. Branches receive their own GIINs, but the first thirteen characters match the parent institution’s, making the relationship visible on the number itself.

Who Needs a GIIN

Three categories of entities register and receive GIINs: participating foreign financial institutions, registered deemed-compliant FFIs, and direct reporting non-financial foreign entities. Sponsoring entities also register and obtain GIINs on behalf of the funds and vehicles they sponsor.

Foreign Financial Institutions

An FFI is any non-US entity that accepts deposits as part of a banking business, holds financial assets for the accounts of others, or is primarily in the business of investing or trading in securities and similar instruments.⁶ That definition pulls in banks, custodial institutions, brokerages, and many investment funds.

FFIs that sign a full FFI Agreement with the IRS become Participating FFIs. They commit to identifying US account holders, performing due diligence on new and existing accounts, and reporting account information annually. Registered Deemed-Compliant FFIs also obtain GIINs but face lighter reporting requirements, usually because their home country has an intergovernmental agreement (IGA) with the United States. FFIs in Model 1 jurisdictions report US account information to their own government’s tax authority, which then passes it to the IRS. FFIs in Model 2 jurisdictions report directly to the IRS, much like a Participating FFI.⁷ The home jurisdiction’s IGA model dictates which registration category applies.

Direct Reporting NFFEs

A Non-Financial Foreign Entity generally does not need a GIIN. There is an exception, though. A Direct Reporting NFFE, meaning one that elects to report its substantial US owners directly to the IRS rather than passing that information through withholding agents, must register and receive a GIIN.⁸ These entities register through the same online system as FFIs.

Who Doesn’t Need a GIIN

Not every foreign entity receiving US-source payments has to register. Two groups fall outside the requirement, and it’s worth checking against them before starting a registration.

Active and Passive NFFEs

An Active NFFE, meaning one where less than 50% of its gross income is passive (dividends, interest, rents, royalties, annuities), is exempt from withholding without a GIIN.¹⁰ It certifies its status on Form W-8BEN-E and moves on.

A Passive NFFE has a higher bar. Because more than half its income comes from passive sources, it must disclose any substantial US owner (a US person owning more than 10% of the entity) on Form W-8BEN-E, and the withholding agent reports those owners to the IRS. If the Passive NFFE certifies it has no substantial US owners, it avoids withholding without a GIIN. If it cannot or will not certify, the 30% withholding applies.¹

Certified Deemed-Compliant FFIs

Certain FFIs qualify for exempt status without registering. These include local banks with no more than $175 million in assets (and no more than $500 million across all related entities), financial institutions where no account exceeds $50,000 in value and total assets stay below $50 million, and certain retirement funds and nonprofit organizations. These entities certify their status on Form W-8BEN-E as a Certified Deemed-Compliant FFI or Non-Reporting IGA FFI and skip registration entirely.

How to Register

Registration happens through the IRS FATCA Registration System, a secure online portal.¹¹ Before opening an account, the institution designates a Responsible Officer. The RO signs the FFI Agreement, certifies compliance, and serves as the IRS’s point of contact for all FATCA matters.¹² The institution also determines its correct FATCA classification (Participating FFI, Registered Deemed-Compliant FFI, Sponsoring Entity, and so on) based on its business activities and its jurisdiction’s IGA status. The paper equivalent of the online registration is Form 8957.⁸

Once the IRS approves the registration, the institution receives a Notice of Registration confirming its GIIN. Receiving the number is only half the battle. The GIIN must appear on the published IRS FFI List before withholding agents will rely on it, and the list is updated monthly.¹² An FFI that has its GIIN but hasn’t yet appeared on the list is effectively treated as nonparticipating until the next update. Plan ahead. Do not wait until a GIIN is urgently needed for a transaction.

Keeping the GIIN Active

A GIIN isn’t a one-time credential. The Responsible Officer must keep the institution’s registration data current through the online portal. Changes to the institution’s name, address, classification, or corporate structure need to be reported promptly.¹¹ Falling behind can result in removal from the FFI List, which triggers 30% withholding on all incoming US-source payments until the information is corrected and the list is refreshed.

Participating FFIs also recertify their compliance every three years. The first certification period starts on the effective date of the FFI Agreement and runs through the end of the third full calendar year, and each subsequent period covers the next three calendar years. The certification must be submitted through the FATCA registration system by July 1 of the year following the end of the certification period.¹² The Responsible Officer confirms that the institution has maintained its compliance program, performed required due diligence, reported accurately and on time, and handled any compliance failures appropriately. There is no waiver. If the RO selects “unable to complete certification,” the IRS treats that as an admission of noncompliance.

If an institution fails to certify or otherwise falls out of compliance, the IRS follows a notice process: a first notice, a second notice, then a termination notice. Termination removes the GIIN from the FFI List, and every US-source withholdable payment the institution receives after that gets hit with 30% withholding. A terminated entity cannot simply re-register for a new GIIN. The IRS reviews new registrations and will reject any that come from previously terminated entities trying to start fresh.¹³ The entity must instead contact the IRS using the information in the termination notice and apply for reinstatement. That review can take 60 to 180 days, or longer if the IRS needs additional information, and the institution stays off the FFI List and subject to withholding the entire time.¹²

1
Office of the Law Revision Counsel. 26 USC 1471 – Withholdable Payments to Foreign Financial Institutions
2
Internal Revenue Service. Foreign Account Tax Compliance Act (FATCA)
3
Internal Revenue Service. FATCA Foreign Financial Institution List Search and Download Tool
4
Office of the Law Revision Counsel. 26 USC 1473 – Definitions
5
Internal Revenue Service. GIIN Composition
6
Internal Revenue Service. Summary of FATCA Reporting for US Taxpayers
7
Internal Revenue Service. FATCA Information for Governments
8
Internal Revenue Service. About Form 8957 – Foreign Account Tax Compliance Act (FATCA) Registration
9
Internal Revenue Service. Frequently Asked Questions (FAQs) – FATCA Registration System
10
Internal Revenue Service. Instructions for Form 8966 (2025)
11
Internal Revenue Service. FATCA Foreign Financial Institution Registration
12
Internal Revenue Service. Overview of FATCA Certification Process
13
Internal Revenue Service. Frequently Asked Questions (FAQs) FATCA Compliance – Legal