US persons include all natural persons, i.e. US citizens (including those holding dual citizenship), US residents (principal or secondary place of residence), holders of a permanent residence and work permit (e.g. a US Green Card) and all those that were present in the USA for more than 31 days in the current year and for more than 183 days in the last three years (each day or presence during the current year counts as one full day, each day during the first preceding year counts as one third of a day, and each day during the second preceding year counts as one sixth of a day). Legal entities that are established or organised under US law or that are domiciled in the USA are also considered US persons. Such US persons are treated the same as persons who might be liable to for tax in the United Sates (e.g. second domicile, joint tax return with a US person, waiver of US citizenship or residence permit after long-term residence, other reasons). The question regarding US person and US tax liability status applies to both natural and legal persons.