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Do you have to file a Luxembourg tax return?
Many employees are not obliged to file — and are better off doing it anyway. Here is how to tell which side you are on.
Compulsory, or voluntary
Withholding at source settles the tax of many employees with no further formality. A return becomes compulsory above certain income thresholds, where there are multiple income sources, foreign income to take into account, or where assimilation to resident status has been requested. Outside those cases it remains possible voluntarily — and that is often where money comes back.
What is deductible
The classic items: mortgage interest on a main residence, pension and insurance contributions, home-savings plans, commuting costs, childcare costs, maintenance payments. For a cross-border worker, commuting costs often weigh more than expected, and a voluntary return puts them to work where withholding at source largely ignores them.
The calendar
The return covers the past calendar year and is filed the following year, online through MyGuichet or on paper. Deadlines have been relaxed in recent years, but asking for an extension beats filing late. Keep payslips, interest certificates, insurance statements and childcare receipts: the deduction rests on the file, not on the ticked box.
When to get help
A single salary, no property and no working spouse abroad: the return is straightforward to do yourself. Income in two countries, a mortgage, an assimilation request or a mid-year change of situation: the cost of an accountant often pays for itself in the first year. Cross-border workers' associations also run advice sessions, at a fraction of the price.
