The Luxembourg tax authority invites you, generally by letter, to prepare your annual tax return before 31 March.
However, this date is a recommendation and the actual deadline is 31 December of year n+1 (for income in year n).
After this date, the Luxembourg tax authority will no longer take any tax deduction into account. whether from special expenses, extraordinary expenses,…
Applies for married taxpayers (resident or non-resident) willing to change their taxation method (e.g. switching from a joint to an individual taxation method or vice-versa). For these cases, the deadline is 31 March.