🧾 Can I skip filing a tax return in Luxembourg?

With conditions

Quick answer

Often yes — the "everyone must file" myth is false. The default regime for a Luxembourg employee is withholding at source, which counts as final taxation. The obligation only arises if you cross a threshold: taxable income above €100,000, more than €600 of income not withheld at source, an additional tax card with more than €36,000 / €30,000, or more than €1,500 of investment income. But the opposite myth costs just as much: "I don't have to file, so there is nothing in it for me." Wrong — the annual adjustment (form 163) exists precisely to reclaim overpaid tax. Not filing when you are not obliged to often means leaving money with the State.

📋 The rules

Deadline: since tax year 2022, the return must be filed by 31 December of the following year. For the 2025 tax year, that means 31 December 2026.
Residents with only non-withheld income: filing is compulsory where taxable income exceeds €12,438 (threshold published by the tax administration, page updated 28.10.2024).
Residents with income taxed at source: filing is compulsory where taxable income exceeds €100,000; OR where more than €600 of net income is not subject to withholding; OR with a flat-rate additional tax card and taxable income above €36,000 (classes 1 and 2) or €30,000 (class 1a); OR where investment income or directors' fees exceed €1,500; OR where you opt for joint or individual taxation.
Non-residents: compulsory for employees working in Luxembourg for at least 9 months of the year on a continuous basis whose taxable income exceeds €100,000 — or €36,000 / €30,000 with an additional tax card. Also compulsory where gross directors' fees exceed €100,000.
Filing on request: any taxpayer must file if the tax administration asks them to, even outside these thresholds.

🔓 Exceptions

The annual adjustment (form 163): employees and pensioners not subject to assessment who want to regularise their withholdings file an adjustment, not a return — also by 31 December of the following year. It is not an obligation, it is an option that pays.
Taxation on request: some taxpayers (mortgage interest on their home, landlords, dividend recipients) can ask to be assessed in order to claim deductions they would otherwise lose.
Irrevocable options: requests for joint or individual taxation must be submitted by 31 December of the following year and cannot be revoked. The choice is final.

⚠️ Penalties & fines

A tax surcharge of up to 10% of the tax assessed for late or missing filing, a penalty payment preceded by a formal demand, and above all, if you refuse, an EX OFFICIO ASSESSMENT by estimation that the tax office is obliged to make. That is where it hurts: an ex officio assessment estimates your income without any of your deductions — business expenses, special expenses, allowances, all gone. On top come late-payment interest of 0.6% PER MONTH (7.2% a year), which also accrues on the surcharge itself: interest running on the penalty.

📎 Official sources

Last verified: 2026-07-12

❓ Frequently asked

Do I have to file a return if I am an employee?

Not necessarily: withholding at source counts as final taxation for most employees. The obligation only arises if you cross a threshold, such as €100,000 of taxable income or €600 of non-withheld income.

What is the filing deadline?

It is 31 December of the year following the tax year, and has been since tax year 2022. Many taxpayers still quote 31 March: that date was abandoned and no longer has any legal force.

Is there really a €25,000 fine for filing late?

That figure circulates widely, but the tax administration's own page gives no numerical ceiling for the penalty payment. What is officially sourced is the tax surcharge of up to 10% of the tax assessed.

What happens if I file nothing at all?

The tax office is obliged to proceed with an ex officio assessment by estimation. Your income is then estimated without any of your deductions, and late-payment interest of 0.6% a month is added on top.

Are tax classes 1, 1a and 2 being abolished?

Draft law 8676, tabled on 6 January 2026, provides for a single class "U" from tax year 2028. It is still in committee and has not been voted: the three classes remain fully in force today.

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