The Finnish Tax Administration released Version 3.4 of the FATCA Technical Guidance on September 15, 2025, introducing significant updates primarily driven by the integration of requirements from IRS Notice 2024-78. The most critical changes focus on enhancing data quality for accounts with missing U.S. Taxpayer Identification Numbers (TINs). Filers are now required to report foreign-issued TINs and provide specific address details in such cases.
Key updates also include the enforcement of a stricter format for the DocRefId element, which must now incorporate the Business ID and tax year. The Ilmoitin.fi e-service has been updated with refined automated checks and messaging logic; notably, the placeholder value ‘AAAAAAAAA’ is no longer permissible for organization TINs, and the validation for the IssuedBy attribute for individual TINs has been adjusted to accommodate foreign country codes starting with the 2025 reporting year. Finally, the guidance clarifies the correct application of DocTypeIndic values when deleting previously reported accounts.
Detailed Analysis of Version 3.4 Updates
The following sections provide a comprehensive examination of the changes introduced in the September 15, 2025, release of the FATCA technical guidance.
Integration of IRS Notice 2024-78 Requirements
A central theme of the version 3.4 update is the incorporation of new mandates from IRS Notice 2024-78, which establishes stricter reporting protocols for the 2025, 2026, and 2027 reporting years when a U.S. TIN is missing.
• Reporting of Foreign-Issued TINs: For financial accounts lacking a U.S. TIN, financial institutions must now search their electronic archives for a foreign-issued TIN for the account holder. If found, this identifier (which can include a Finnish personal identity code) must be reported on the FATCA annual information return.
• Mandatory Use of AddressFix Structure: For all accounts with a missing U.S. TIN, the AddressFix structure must be used to report the account holder’s City and Country of residence.
Enhanced Data Formatting and Validation Requirements
Version 3.4 introduces more rigorous data formatting rules and refines the automated validation processes within the Ilmoitin.fi e-service to improve the quality of submissions.
Updated DocRefId Format
The format requirement for the DocRefId element has been updated to be more specific. It is now mandatory for the DocRefId string to include the reporting financial institution’s Business ID and the tax year. The full format is described as the financial institution’s GIIN, followed by a period, followed by a string containing the Business ID, the tax year, and a sequential digit.
• Example of an entire DocRefId string: CAWYDV.00001.SF.246.6606611-7-2018-001-002-003
Changes to Ilmoitin.fi Automated Checks
The list of automated checks performed by the Ilmoitin.fi service has been significantly updated. These checks prevent a return from being sent if errors are detected.
| Data Element(s) | Description of Change in Version 3.4 |
AccountHolder/Individual/TIN <br> SubstantialOwner/Individual/TIN | The automated check for invalid TIN formats (e.g., nine identical characters) will now apply only if the IssuedBy attribute is ‘US’ or is not reported. |
AccountHolder/Organisation/TIN | The value ‘AAAAAAAAA’, which was previously a permissible placeholder, has been removed from the list of allowed exceptions. The check for invalid formats will now reject this value. |
AccountHolder/Individual/TIN/IssuedBy <br> SubstantialOwner/Individual/TIN/IssuedBy | The check that previously required this attribute’s value to be ‘US’ is no longer in force starting from the 2025 reporting year. This aligns with the new requirement to report foreign-issued TINs. |
Modifications to Correction and Deletion Procedures
The guidance provides a specific update related to the deletion of previously reported data, clarifying the use of the DocTypeIndic element.
• Use of DocTypeIndic FATCA3: To remove accounts that were reported previously, filers must use the value FATCA3 (Void data). The guidance now specifies that in such cases, FATCA3 must also be used in the ReportingFI structure, even if only individual accounts within the report are being removed.
Deprecation and Refinement of Data Elements and Messages
The update continues the process of refining the reporting schema by adjusting the use of certain data elements and the logic of system messages.
• Expanded Use of TIN/IssuedBy Attribute: In a significant change effective from the 2025 reporting year, the IssuedBy attribute for an individual’s TIN is no longer restricted to ‘US’. It is now permissible for the value to be the country code of any country that issued the reported Tax Identification Number. This change supports the new requirement to report foreign TINs when a U.S. TIN is unavailable.
• Refined Ilmoitin.fi Messaging: The logic for displaying certain non-blocking warning messages in Ilmoitin.fi has been updated. The following messages will now only appear if the TIN in question is identified as being issued by the United States:
◦ Messages related to AccountHolder/Individual/TIN
◦ Messages related to /Individual/TIN
◦ Messages related to /Individual/TIN and /Individual/BirthInfo/BirthDate