Key legal question
Where was the spouses' principal tax domicile from 2001 onward?
Extracted holding
Their center of personal interests and principal tax domicile was in X. in the canton of Jura.
Extracted reasoning
The house in Jura offered the real family home and materially better living conditions, whereas the stay in Basel-Landschaft was only a modest pied-à-terre near their daughter; alternating stays did not justify an equal dual domicile.