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Do you have to file a tax return every year in Luxembourg?
Filing once doesn't tie you in for life. When is a Luxembourg tax return mandatory, when is it optional, and when is it worth it? Find out on taxx.lu.
You filed a tax return once. And ever since, one question has been nagging: have you just signed up for life?
Good news. You haven't.
In Luxembourg, filing one year doesn't switch on a lifelong subscription. The obligation is judged fresh every year, based on your situation that year. Some years you'll have to file. Others you won't. And sometimes you won't have to, but you'll want to anyway.
Here's how to make sense of it.
The short version
Three scenarios, every year:
- You're required to file.
- You're not required to, but the tax administration (ACD) asks you to, and then it becomes mandatory.
- You're not required to at all, but filing could pay off.
The common thread: nothing carries over automatically from one year to the next. Last year's return doesn't chain you to this year's.
When is a tax return mandatory?
As a resident, you have to file a tax return (form 100) if any of these apply:
- your annual income taxed at source is over €100,000;
- you have more than one salary or pension taxed at source, and your annual income is over €36,000 (tax classes 1 or 2) or over €30,000 (tax class 1a);
- you receive Luxembourg income that isn't taxed at source, such as rental income or earnings from self-employed or freelance work.
A concrete example
You're single, one employer, a salary already taxed at source below €100,000, no other income. You don't have to file. The next year, you rent out a flat: that rent isn't taxed at source. That year, filing becomes mandatory.
The case where you have no choice: the tax administration (ACD) asks you
Here's the nuance behind the myth.
Even if you meet none of the conditions above, you're still required to declare your income if the ACD asks you to. In plain terms: if the tax authority sends you a return to complete, you have to complete it. Whatever your situation.
A request from the ACD isn't optional
If you receive a tax return from the ACD, you're required to respond by the stated deadline, even if you think you owe nothing. If you don't, the tax office can assess your tax on an estimated basis. In other words, without you.
Not required? Filing can still be worth it
This is the scenario plenty of people miss.
You're not required to file, but you may have overpaid during the year. A voluntary return, or an annual adjustment (more on that shortly), squares up your withholdings and claws back any overpayment.
The usual deductions come into play here: loan interest, insurance premiums, home savings, pension provision, childcare costs, donations. Every item can tip the balance in your favour.
Check before you commit
On taxx.lu, you fill in your return and watch your estimated refund update in real time as you go. So you'll know whether filing pays off before you finalise anything. Creating an account and running a simulation is free. The final amount, of course, always rests with the ACD.
The real trap: some choices commit you
Not everything resets each year. Some decisions have a tail.
Requesting tax assimilation (for cross-border workers) or individual taxation automatically triggers assessment. So you go through the return.
And assimilation never renews on its own. Every year, you have to request it again by filing a new return. If it earns you an advantage, the tax class 2 rate for instance, that too has to be reactivated every year.
Assimilation renews every year
The advantage from one year doesn't roll over by itself. Forget to file again and you risk losing it for that year. Keep your supporting documents safe: payslips, foreign income statements, insurance certificates.
Tax return or annual adjustment? Two forms, two jobs
The two get mixed up a lot. They're not in the same league.
- The tax return (form 100): the full route. Mandatory in the cases above, or voluntary to claim all your deductions.
- The annual adjustment (form 163): the light version. For employees and pensioners not subject to assessment who simply want to recover over-withheld tax. As a rule, it can never result in extra tax to pay.
One or the other per year
For any given year, you pick either the tax return or the annual adjustment, never both. If you're unsure where you stand, check the conditions before you file.
How long do you have to file?
You've got time, but not forever.
The return is due by 31 December of the year following the income year. So for a given year's income, you have until the end of the next year.
One thing to keep in mind: if you're not required to file and you submit after that date, your return may no longer be taken into account. For a voluntary step, better not to leave it late.
In short
- Filing once doesn't tie you in for life.
- Each year, the obligation depends on your situation.
- If the ACD sends you a return, you have to complete it.
- Even without an obligation, filing can get money back.
- Some choices, like assimilation or individual taxation, replay every year.
The only question that really matters: this year, do I have to file, and is it worth my while? taxx.lu answers both.
