Guide: Who Must File a Tax Return in Luxembourg?
Every year, the same question comes up: is it a choice or an obligation? Understanding your status is essential to avoid penalties or, on the contrary, to recover overpaid tax.
1. Resident Taxpayers
Mandatory if:
- High income: Above €100,000.
- Multiple sources of income: Over €36,000 (Tax classes 1 & 2) or €30,000 (Tax class 1A).
- Additional income: Over €600 (e.g. rental income).
- Investment income: Over €1,500 of income from movable capital.
2. Non-Residents (Cross-Border Workers)
Mandatory if:
- Assimilation: You have opted to be treated as a resident (assimilated non-resident).
- Thresholds: Income > €100,000 or combined income > €36,000.
- Directors' fees: Luxembourg-source income > €100,000 gross.
- Request: At the request of the Tax Administration.
Deadlines to meet: The tax return must be filed no later than 31 December of the following year (e.g. 31 Dec. 2026 for 2025 income).
The Annual Adjustment (Simplified Option)
If you are not required to file a tax return, this option is available if:
- You were employed in Luxembourg for 9 full months.
- OR 75% of your gross annual remuneration comes from Luxembourg.
Note: Belgian non-residents benefit from a reduced assimilation threshold of 50%.
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