if she spends less than 90 tax days here, then she is non resident - a tax day is not the same as a working day as every time that you arrive or leave is not counted - i.e fly in on a Monday, leave on the Friday, then that's 3 tax days. There are havens like the Bahamas where you can be resident and pay zero tax - though you have to pay $15 mln on property I think the number is, and you also get a Bahamian passport. Then you travel around your different residences in the UK, France and the UsA avoiding any tax.