Tax Return Guide: How to File Your Tax Return
Filing your tax return in Luxembourg can raise many questions, especially if you’ve just moved to the country. Income to report, supporting documents, tax deductions, online filing, deadlines: it’s best to prepare your paperwork systematically.
This guide walks you through the process step by step to help you understand how to file your tax return in Luxembourg, what documents to prepare, what information to verify, and how to submit your return to the Direct Tax Administration.
If you’re not yet sure whether you need to file a tax return, check out our dedicated guide first: Do I need to file a tax return in Luxembourg?
Tax Return: Key Points for Expatriates
- Tax returns in Luxembourg are filed using Form 100 for eligible individuals.
- It can be submitted online via MyGuichet.lu or on paper, depending on your situation.
- The standard filing deadline is December 31 of the year following the tax year.
- You must prepare your pay stubs, bank statements, proof of insurance, childcare expenses, pensions, or foreign income, if applicable.
- A properly completed return may result in a tax refund or a favorable adjustment.
What is the purpose of the tax return in Luxembourg?
The tax return allows the tax authorities to recalculate the exact amount of your tax based on your actual circumstances.
It takes into account your income, your family situation, your tax bracket, any foreign income, as well as the tax deductions or tax credits to which you may be entitled.
Once your return has been processed, the tax authorities may:
- refund you for any overpaid tax;
- request additional tax from you;
- send you a request for additional information or supporting documents.
To better understand how the tax system in Luxembourg works, visit our reference page: Taxation in Luxembourg: A Practical Guide for Expats and Newcomers.
Key elements for filing your tax return
- Form 100: Income tax return form for individuals.
- December 31: Standard filing deadline for the previous tax year.
- MyGuichet.lu: platform for filing your tax return online.
- 1 calendar year: the return covers income earned from January 1 to December 31.
- Currently3 tax brackets: bracket 1, bracket 1a, and bracket 2.
What documents should you prepare before filing your return?
Before you begin your tax return, gather all the necessary documents. This will help you avoid omissions, errors in amounts, or additional requests from the tax authorities.
| Document | What is it used for? | Examples |
|---|---|---|
| Pay stub | To report your Luxembourg professional income | Annual certificate issued by the employer |
| Bank statements | Reporting certain interest, loans, or financial income | Interest expense, mortgage, bank accounts |
| Insurance certificates | Claiming certain tax deductions | Life insurance, liability insurance, supplemental health insurance |
| Proof of family expenses | Claiming certain child- or family-related expenses | Daycare, after-school care, child support |
| Documents related to foreign income | To ensure your tax rate is calculated correctly | Rental income, dividends, foreign pension |
| Proof of donations | Claim tax-deductible donations | Certification from a recognized organization |
How to file your tax return step by step?
Filling out a tax return follows a simple process: identify your situation, report your income, add deductible expenses, verify the information, and then submit the form.
Step 1: Verify your personal and family situation
Before reporting your income, verify the information regarding your personal situation: address, marital status, household composition, dependent children, marriage, partnership, or separation.
Your family situation can have a significant impact on your tax bracket and the applicable tax benefits. For more information, consult our guide on types of unions and their tax implications in Luxembourg.
Step 2: Report your Luxembourg income
You must report income earned in Luxembourg during the relevant tax year. This may include wages, pensions, self-employment income, business income, or rental income.
Employees will generally find the necessary information on their annual salary statement.
Step 3: Report foreign income if your situation requires it
Expatriates living in Luxembourg may sometimes retain income in their home country: rental property, bank interest, dividends, pensions, or other investment income.
This income may need to be reported on your Luxembourg tax return, even if it has already been taxed abroad. It may be used, for example, to determine the tax rate applicable to taxable income in Luxembourg.
Step 4: Report deductible expenses
Deductible expenses help reduce your taxable income. They may include insurance, retirement savings, home savings plans, mortgage interest, child care expenses, alimony, or charitable donations.
To learn about the main expenses covered, consult our comprehensive guide to tax deductions in Luxembourg.
Step 5: Review, sign, and submit the return
Before submitting, carefully review the reported amounts, the completed sections, and the supporting documents you have on hand.
An error or omission may result in a request for correction, longer processing times, or a less favorable tax assessment.
How do I file my tax return online on MyGuichet?
You can file your tax return online via MyGuichet.lu if your situation allows it. This solution makes it easier to enter, track, and submit your return.
To file your taxes online, you generally need to:
- log in to your MyGuichet.lu account;
- select the income tax filing option;
- fill out the sections that apply to your situation;
- add information regarding your income and expenses;
- check the data you entered;
- sign and submit the return electronically.
Your return must be validated using a digital identity verification system.
To better understand online administrative procedures in Luxembourg, please also visit our page dedicated to administrative procedures in Luxembourg.
When should you file your tax return in Luxembourg?
Luxembourg uses the calendar year for income tax: the return covers income received between January 1 and December 31.
The return must generally be filed by December 31 of the year following the tax year.
| Situation | Deadline | Procedure |
|---|---|---|
| Income received in year N | By December 31 of year N+1 | Prepare and submit the return by the deadline. |
| Declaration requested by the tax authority | By the specified deadline | Respond to the request from the Direct Tax Administration. |
| Voluntary return | Meet the applicable deadline | File the return to claim deductions or a refund. |
Checklist: Before submitting your tax return
- Verify your family status and tax bracket.
- Gather your pay stubs and income statements.
- Identify any foreign income to report, if applicable.
- Add any deductible expenses for which you are eligible.
- Keep receipts for insurance, childcare costs, loans, donations, or pensions.
- Verify the accuracy of the amounts reported.
- Verify your bank account information.
- Submit your tax return before the deadline.
What happens after you submit your tax return?
After receiving your return, the Direct Tax Administration reviews the information provided.
It may then:
- validate the reported information;
- request supporting documents or additional information;
- calculate the final tax amount;
- issue a tax notice;
- indicate an amount due or a refund to be received.
Any refund will be deposited into the bank account provided to the tax authorities. If a balance is due, the tax notice will specify the payment terms and deadlines.
For your banking procedures in Luxembourg, consult our guide on bank accounts in Luxembourg.
Tax Return: Common Mistakes
- Confusing withholding tax with a full tax return.
- Forgetting to report certain foreign income or additional income.
- Failing to report certain deductible expenses.
- Reporting amounts without keeping supporting documents.
- Using the wrong section on the form.
- Waiting until the last few days to prepare your tax return.
- Failing to respond to a follow-up request from the tax authorities.
Tax guides to consult based on your situation
- Understanding taxation in Luxembourg
- Find out if you need to file a tax return
- Identifying the main tax deductions
- Understanding withholding tax
- Understanding personal income tax
- Understanding the tax implications of marriage or civil partnership
Tax Return Guide: Important
Every tax situation is different. The information you need to report depends on your tax residence, your family situation, the nature of your income, your deductible expenses, and whether you have any income from abroad.
The information presented on this page is for informational purposes only. If in doubt, it is recommended that you consult a professional or contact the Direct Tax Administration.
Filling Out Your Tax Return in Luxembourg: Key Points
Filing a tax return in Luxembourg allows you to regularize your tax situation, report all your income, and claim the deductions to which you are entitled.
For expats and newcomers, the main challenge is to prepare the documents properly, understand the key sections, and meet the deadlines. A correctly completed return can prevent errors, speed up processing, and sometimes result in a tax refund.
FAQ: Filing a Tax Return in Luxembourg
How do you file your tax return in Luxembourg?
You must gather your documents, fill in your personal information, report your income, list deductible expenses, verify the amounts, and then submit your return via MyGuichet.lu or on paper, depending on your situation.
Which form should you use to file your taxes?
Taxpayers subject to personal income tax generally use Form 100. This form can be completed online or on paper, depending on the situation.
Can you file your tax return online?
Yes. You can file your tax return online via MyGuichet.lu if your situation allows it. You must have a means of electronic identification to sign and submit your return.
What documents do you need to prepare?
In particular, prepare your pay stubs, bank statements, insurance documents, proof of childcare expenses, donation receipts, loan-related documents, and proof of foreign income if applicable.
When should you file your tax return?
The return must generally be filed by December 31 of the year following the tax year in question. It is recommended that you do not wait until the last few weeks to prepare your return.
Do you need to report foreign income?
In many cases, foreign income must be reported in order to correctly determine the applicable tax rate. This does not necessarily mean that it will be taxed a second time in Luxembourg.
When will I receive the tax assessment notice?
The tax assessment notice is sent after your return has been processed by the Direct Tax Administration. The timeframe may vary depending on the filing period, the complexity of the case, and any requests for supporting documents.
Can you get a tax refund?
Yes. If the tax withheld at source exceeds the tax actually owed after taking your situation and deductions into account, the tax authority may refund the overpayment.
Should I consult a tax advisor?
A tax advisor can be helpful for your first tax return, especially if you have foreign income, real estate assets, self-employment income, a complex family situation, or questions about applicable deductions.
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