FFIs

FFIs is an acronym that may refer to more than one concept in finance and computing. The two most common usages are Foreign Financial Institutions and Foreign Function Interfaces.

Foreign Financial Institutions

In tax and compliance contexts, FFIs refer to foreign institutions that hold financial accounts for individuals or entities. Under the U.S. Foreign Account Tax Compliance Act (FATCA), FFIs are required to report information about accounts held by U.S. taxpayers to the Internal Revenue Service or to their local tax authority through intergovernmental agreements. FFIs can include banks, brokerage firms, mutual funds, insurance companies, and other financial entities. Non-financial foreign entities (NFFEs) are treated separately for FATCA purposes. Failure to obtain required reporting or to comply with FATCA terms can result in withholding taxes on certain U.S.-source payments to the FFI. The FATCA framework has led to widespread cross-border information sharing and withholdings, and it is implemented through both domestic law and international agreements.

Foreign Function Interfaces

In computing, FFIs refer to interfaces that allow code written in one programming language to call functions or use data types from another language. FFIs enable interoperability with libraries and components across language boundaries, facilitating the reuse of existing code and system integration. Common examples include the Java Native Interface (JNI), Python’s C API and the cffi library, and Rust’s ability to interface with C libraries. Important considerations for FFIs include ensuring compatibility of calling conventions and data representations (ABI and type mappings), memory management across boundaries, potential performance overhead, and safety guarantees when crossing language boundaries.

The term FFIs thus has multiple domain-specific meanings; context determines which interpretation is intended.