Your first year in Luxembourg: why you may get tax back
If you started working in Luxembourg part-way through the year, you may have paid more tax through your payslip than you owe for the year. This guide explains why, and the two ways to claim the difference back.
Why you may have overpaid
Tax taken from your pay is an advance. It is worked out on your monthly pay as if it lasted all year, so a part year can leave you with too much withheld. Costs such as insurance, loan interest or commuting are often not on your tax card, so your payslip does not reflect them either.
Route 1: the annual adjustment
The annual adjustment (décompte annuel) is meant for employees who are not assessed through a full tax return. Residents use form 163 R and non-residents use form 163 NR. The 163 R goes to the tax office by post, not by email; there is also a questionnaire on MyGuichet.
Route 2: the tax return
The tax return (form 100) is needed, for example, to deduct home-loan interest. It is compulsory in some cases: for instance accessory income over €600 that was not taxed at source, taxable income over €100,000, or several tax cards with taxable income above €36,000 in class 1 or 2, or €30,000 in class 1a. The tax office can also ask you for one. For 2025, the window for form 100 opened on 7 April 2026.
Deadline and late filing
For tax year 2025 the deadline is 31 December 2026 for both routes. For the annual adjustment it is a firm deadline with no extension. Late or missing returns can bring surcharges and interest.
Getting your refund
Any refund is paid to the bank account you give the tax office.
How we help
We check which route fits your situation, prepare it and, with the Premium package, file it for you.
Checked on 8 Oct 2026 for tax year 2025
General information from official sources, not tax advice. Your situation can differ. We check everything when we prepare your return.
Official sources
- ACD: annual adjustment (décompte)(opens in a new tab) (page updated 24 Feb 2026)
- ACD: forms for the annual adjustment(opens in a new tab) (page updated 15 Jun 2026)
- guichet.lu: annual adjustment for residents(opens in a new tab) (page updated 7 Apr 2026)
- guichet.lu: the tax return(opens in a new tab) (page updated 7 Apr 2026)
- ACD: FAQ for residents(opens in a new tab)