The Full Form of GIIN is Global Intermediary Identification Number.

GIIN is an abbreviation of Global Intermediary Identification Number. The FATCA Registration System approves foreign financial institutions (FFI), financial institution (FI) branches, direct reporting non-financial foreign entities (NFFE), sponsoring entities, sponsored entities, and sponsored subsidiary branches. Institutions and entities assigned a GIIN can use it to identify themselves to withholding agents and tax administrators for FATCA reporting purposes.

The GIIN, formatted as XXXXXX.XXXXX.XX.XXX, is a 19-character identification number made up of several identifiers. These characters will never contain the letter “O”.