Your 2025 Luxembourg return, ready to sign.

Answer the questions. SimpleTax.lu writes them into the official Form 100 and shows what you are likely to get back, or still owe.

Prepared return 5.99 euro

You pay by card when you download the form.

This version is for a resident employee in tax class 1: single or divorced, under 64 on 1 January 2025, with no child in the household.

A child lived in my household in 2025 Civil status

First name

Last name

National identification number, 13 digits Place of birth Profession

Phone

Address

Street Street number

Postcode

City

Country of the address Tax office

Filled from your address when the street or postcode is recognised. You can change it.

File number, if a previous assessment shows one

Collect these papers first.

You will type the figures from them. SimpleTax.lu does not scan the certificates.

Salary certificate, one per employer

Ask payroll, or download it from the employer portal. On the Luxembourg certificat de salaire, use the gross pay on line 10 (letter A), the social-security total on line 18, the wage tax withheld on line 40 (letter E), and any employee supplementary pension on line 25.

Mortgage certificate, if you own the home you live in

The bank posts it in online banking in the spring, often under tax documents. You need interest paid in 2025, principal still outstanding on 31 December, and the date the home became available to live in.

Insurance, savings, and gifts

The annual bill for each private policy, such as family liability. A home-savings statement, if you have one. An article 111bis or PEPP statement, with the premiums and the contract dates. Donation receipts. These are separate from the pension line on the salary certificate.

Tax card, and any investment statement

The tax card shows the commuting deduction under FD. A dividend or interest statement is needed only if you received income that was not already taxed in full in Luxembourg. Interest that suffered the final Luxembourg savings withholding stays off the return.

Salary

One block per employer, up to two. The gross figure is line 10, before social security is taken off. Social security is deducted later, on its own line.

I received sickness, maternity, accident, or unemployment benefits I had a third contract, or other pay that is not on the two certificates The certificate shows exempt overtime, or night, Sunday, or holiday supplements Commuting deduction, euro

On the tax card this is FD. It is 99 euro for each distance unit after the first 4, and it stops at 2,574. The units are the straight-line distance between the two communes, not the kilometres you drive. Enter 0 if you live within 4 units of work.

Town where you work Professional expenses, in euro

The minimum is 540 euro for a full year. Enter a higher figure only if you have actual costs above that, with the receipts.

The home you live in

Did you pay mortgage interest on the home you live in during 2025?

No Yes

Deductions

These are amounts you paid yourself. Social security and the employer pension are already taken from the salary certificate. If everything in this basket is under 480 euro, the return uses 480 euro instead. Donations sit outside that minimum.

I paid private insurance, such as family liability, life, accident, or top-up health I paid into a private old-age contract (prévoyance-vieillesse, article 111bis) I paid into a pan-European personal pension (PEPP, article 111ter) I paid into a home-savings plan (épargne-logement) I paid voluntary social security, or bought pension periods I paid interest on a car loan or another personal loan I paid maintenance to a former spouse I gave money to a recognised charity

Dividends and interest

Leave this at zero if your only investment income already suffered the final Luxembourg withholding on a savings account. That interest is not declared.

Luxembourg dividends, gross, euro

The return keeps half. Type the gross amount from the statement.

Luxembourg tax already withheld on those dividends, euro Dividends from a country with a tax treaty, gross, euro

Half of these are taxable too. France, Germany, and Belgium are treaty countries.

Foreign tax on those dividends, euro Interest, and dividends from a country without a treaty, euro

Interest that did not suffer the final Luxembourg savings withholding. This amount is taxable in full.

Foreign tax on that interest or those dividends, euro

After the half-dividend, a 25 euro minimum and a 1,500 euro band come off. Foreign tax is credited only up to the Luxembourg income tax on that income.

Your estimate

This is an estimate. It uses the figures you typed and the published 2025 scale. The assessment from the tax office can be a different amount, and that assessment is the one that counts.

Then file it on MyGuichet

Prepare the PDF here, then upload and sign on MyGuichet. You need LuxTrust or a Luxembourg eID to sign.

Do not change the file name, and do not edit the PDF in another program after Acrobat Reader.
Skip the red “Signer dans MyGuichet.lu” button inside the PDF. Upload on the website instead.
Late in the year MyGuichet can be slow. If upload or signing fails, try again later.

Download Form 100 below.
Open the file in Adobe Acrobat Reader on a Mac or Windows computer (not on a phone, and not only in the browser). The free Reader is enough. You do not need to change any figures. Let Reader run the form’s own sums, check the pages look right, then choose File → Save.
Go to Services catalogue on MyGuichet, log in if asked, and stay on Services catalogue.
Under New procedure through the submission of a document, drag and drop your saved Form 100 PDF (or browse to it).
Add these papers as supporting documents:
Click Sign, follow LuxTrust / eID, then Send. The tax office is on the top left of page 1 of the form.

MyGuichet Services catalogue: open Services catalogue, then drop the Form 100 PDF in the document submission box — After login: Services catalogue, then drop your Form 100 in the box on the right.

By downloading the filled form, you acknowledge that SimpleTax.lu has no legal responsibility if the amount you pay, or the amount you get back, differs from this estimate.