I would like some tax guidance. My dad is an Austrian citizen and has lived and worked in the US for most of his life. He retired in 2014 and split his time between the US and Austria. My dad held a green card for many years but is now a non-resident alien and lives in Austria. My dad has a Roth IRA retirement account in the US with over a million dollars in assets. I have questions regarding the Austria-US Estate Tax Treaty and how much estate tax my siblings and I will have to pay when my dad passes away, given his current situation? My siblings and I are US citizens who will be inheriting the Roth IRA- will we be taxed the standard 40% estate tax that is imposed on nonresident aliens? And how does the Austria-US Estate Tax Treaty come into play? Thanks for any info!