All adults of Swiss nationality or holders of a C permit who live in Switzerland without interruption from of the fiscal year, from January 1st to December 31st, are subject to taxes on income and on capital on an unlimited basis: in this sense, they have the obligation to file a tax return according to the time limit of each canton, even if they have no income. All income and wealth in Switzerland and abroad relating to this period must be declared.

Underage children are required to file income tax returns once they become gainfully employed, note that only Ticino canton indexes the income of minor children only when they become a majority.