Key legal question
Whether the tax authorities had to limit the married-couple surcharge to 10% over comparable cohabiting couples
Extracted holding
No. The cantonal law, aligned with LHID, and the Federal Court's case law accept the unequal treatment; the former 10% practice was not binding.
Extracted reasoning
Art. 11 LHID requires appropriate relief for married couples, but federal case law tolerates the disparity between married couples and cohabitants. After harmonization, the canton could abandon its previous practice because it conflicted with the mandatory federal framework.