What are the tax return deadlines in Switzerland and do they vary by canton?

Switzerland's tax return deadlines vary by canton and are set by each cantonal tax authority. The standard deadline in most German-speaking cantons is March 31 for the previous tax year. French-speaking cantons typically set a deadline of March 15 or the end of March. Canton Ticino uses an end-of-March deadline. The federal direct tax return follows the same deadline as the cantonal return since they are filed together.

Extensions are routinely granted and easy to request. Most cantons allow a first extension to September 30 on a simple written or online request submitted before the original deadline, typically free of charge. Further extensions to November 30 or even December 31 are possible in some cantons for reasonable cause, sometimes with a small fee. Tax advisers handling large client volumes often secure blanket extensions for all their clients.

Filing late without an extension can result in a surcharge or fixed penalty, and in cases of persistent non-compliance the authority may file a default assessment (Ermessensveranlagung) on estimated income, typically set higher than actual income. Quellensteuer payers who want a corrective assessment must meet the specific request deadline set by their canton, usually March 31 of the year following the tax year.

This is general information only, not professional tax advice. Consult a qualified tax professional for your specific situation.