In order to obtain the reimbursement of any excess tax withheld at source, employees or pensioners can - upon request - regularise their tax situation according to their personal situation:
- either through taxation by assessment (form 100).
- or by way of an annual adjustment (form 163 R);
When downloading the PDF form, it is recommended that you save the form on the hard disk, then run Acrobat Reader and open the form from inside the Acrobat Reader (file, open) to avoid potential issues with how the form is displayed and how automatic calculations are performed.
Who is concerned
The tax return (form 100) should be filed with the relevant tax office preferably by 31 March of the year following the tax year in question, and observing the specific submission deadlines indicated by the different departments of the Luxembourg Inland Revenue (Administration des contributions directes - ACD).
Example: for the tax year N, the tax return should be submitted preferably before 31 March of the year N+1.
Persons who require an extension of the deadline for submitting or filing the tax return should apply for the extension (preferably by fax or post) to the competent tax office.
If the taxpayer refuses to file their tax return, the tax office will be forced to determine the tax liability using the estimated assessment procedure (taxation d'office par voie d'estimation).
How to proceed
General principles of taxation
Exempt income is not taxable as such, but may be taken into account in determining the applicable tax rate for non-exempt taxable income.
Simple example illustrating the case of a single (unmarried) taxpayer (tax class 1):
Taxable income in Luxembourg (salary): EUR 40,000 (indigenous income = income from Luxembourg source)
Rental income from a property located in a country with which Luxembourg has a double taxation agreement (tax-exempt income in Luxembourg): EUR 10,000.
The total taxable income taken into account to calculate the tax rate: EUR 10,000 + 40,000 = EUR 50,000.
According to the 2017 income tax scale, the tax due for an income of EUR 50,000 (tax class 1) amounts to EUR 9,106. Thus, the overall tax rate is 9,106 / 50,000 = 18.21 %. To this tax rate is added the 7 % contribution to the employment fund, which brings the applicable rate to 19.48 %.
This rate is applied only to non-exempt income, i.e., in this case, to the EUR 40,000.
Tax due on taxable income in Luxembourg, based on the tax scale: 40.000 × 19.48 % = EUR 7,792.
Taxpayers who are taxed jointly only file a single tax return listing all of their income. The tax is determined on the basis of the taxpayers' aggregate joint net income, and is payable by them as a unit.
Determination of taxable income
Taxpayers are liable for tax in Luxembourg on the income that they earn, which is subdivided into 8 categories:
- business profit;
- agricultural and forestry profits;
- earnings from self-employment;
- net income from paid employment;
- net income from pensions or annuities;
- net investment income;
- net rental property income;
- and net miscellaneous income.
Taxable income is determined by adding together the different categories of net income, and deducting special expenses, such as:
- allowances paid to a divorced spouse or other long-term allowances;
- interest payments on consumer loans used to finance the purchase of a car, movable assets, etc. (note that interest in connection with existing buildings or those under construction are not considered as special expenses, and must be reported on sheet L, form 100);
- insurance contributions and premiums;
- contributions to supplementary pension schemes;
- gifts or donations.
Income subject to tax (taxable income) is equal to the income deferred at the end of the tax form, minus certain deductions (e.g.: allowance for extraordinary expenses borne by the taxpayer).
This adjusted taxable income is then matched against the income brackets in a progressive income tax scale.
Submission of the tax return
In principle, each February, taxpayers should receive:
- either an invitation to download and electronically complete the tax return forms provided on Guichet.lu or on the website of the Luxembourg Inland Revenue (ACD);
- or a paper form (form 100) by mail.
The declarant shall deliver or send the completed and signed declaration to the competent tax office.
Even if the taxpayers have received a paper form, they can complete the tax return forms electronically and send them to the ACD via MyGuichet, along with the various supporting documents.
Watch the tax return tutorial on MyGuichet.
The declarant must attach certain supporting documents to his declaration:
- a compensation certificate (annual salary statement) and/or annual pension statement;
- a certificate showing the amount of interest paid on a mortgage or personal loan taken out during the tax year in question (annual financial statements);
- a civil partnership certificate when joint taxation is requested for the first time for the tax year in question.
In the event of an oversight or an error in the tax return—regardless of whether the return is sent by post or electronically—taxpayers should contact the competent tax office.
Any request for correction must necessarily be communicated in writing to the competent tax office within 3 months of the taxpayer sending the declaration.
Setting the amount of tax payable
The income tax payable by the taxpayer is determined by matching the rounded-off adjusted taxable income against the income brackets in a progressive tax scale.
The progressive scale for the 2017 tax year is divided into 23 incremental tax brackets ranging from 0 % to 42 % plus an additional 7 % to 9 % for the contribution to the employment fund.
Owing to the progressive nature of the scale, taxpayers with higher income pay proportionally more tax than taxpayers with lower income.
Forms / Online services
Income tax return for resident and non-resident natural persons (form 100)
Déclaration pour l'impôt sur le revenu pour personnes physiques résidentes et non résidentes (modèle 100)
Einkommensteuererklärung für ansässige und nicht ansässige Personen (Vordruck 100)