Foreign Account Tax Compliance Act (FATCA)

FATCA requires Financial Institutions outside the US to pass information about their US customers to the tax authorities

The Foreign Account Tax Compliance Act (FATCA) focuses on reporting by foreign financial institutions about financial accounts held by U.S. taxpayers or foreign entities in which U.S. taxpayers hold a substantial ownership interest. In accordance with current guidance Germany has signed a so-called Intergovernmental Agreement (IGA) with the U.S., allowing foreign financial institutions (FFIs) in Germany to comply with FATCA obligations.

Under FATCA FFIs need to register with the IRS and agree to report to the IRS certain information about their U.S. accounts, including accounts of certain foreign entities with substantial U.S. owners. An FFI that registers on the FATCA Registration Website upon approval will receive a Global Intermediary Identification Number (GIIN) from the IRS. The IRS will publish a list of registered and approved FFIs and their GIINs every month (see FATCA Foreign Financial Institution List)
The IRS assigned the following GIIN to Aareal Bank AG Wiesbaden, Germany:
NLT7B2.99999.SL.276 (Reporting Financial Institution under a Model 1 IGA).
List of GIINs of Aareal Bank AG branches:

France NLT7B2.99999.BR.250
Ireland NLT7B2.99999.BR.372
Italy  NLT7B2.99999.BR.380
United Kingdom NLT7B2.99999.BR.826
Poland NLT7B2.99999.BR.616
Sweden NLT7B2.99999.BR.752