Question juridique clé
Whether the appellant's main tax domicile from 1 January 2003 was in Y./LU or Z./ZG
Solution extraite
The main tax domicile remained in Z./ZG; the Luzern authorities infringed the constitutional ban on intercantonal double taxation by asserting domicile in Y./LU.
Motifs extraits
Although there was a presumption in favor of the weekly residence/workplace, it was rebutted by the appellant's strong and continuing family and social ties to Z./ZG, regular returns there, use of the family home, and the weaker connection to the modest weekly apartment in Y./LU.