Americans in Luxembourg: Your US Tax Return Checklist 🇱🇺
What documents do US taxpayers in Luxembourg need to file? You’ll need your Certificat de Salaire (Fiche de Retenue d’Impôt), Luxembourg tax return (Déclaration d’Impôt) if filed, proof of taxes paid to Administration des Contributions Directes (ACD), travel records showing time in each country, and foreign account information if balances exceeded $10,000 USD at any time during the tax year.
Key facts for US taxpayers in Luxembourg:
- Both countries tax worldwide income; the US-Luxembourg tax treaty prevents double taxation but doesn’t eliminate filing requirements
- June 15 automatic filing extension applies if you live outside the US on the regular April deadline
- Luxembourg tax year aligns with the US calendar year (January 1 – December 31)
- FBAR required if total foreign accounts (including Luxembourg bank accounts, pension plans, investment accounts) exceeded $10,000 USD at any point during the tax year
- Luxembourg retirement accounts (pension complementaire, régime de pension) have special treaty treatment
- Luxembourg social security contributions do NOT qualify for US tax credits
- Foreign Tax Credit often provides better results due to Luxembourg tax rates, though this requires analysis of each individual specific situation
📋 Filing Status & Household Information
Your filing status affects tax rates, deductions, credits, and multiple downstream decisions.
What you need:
- Full legal names (must match Social Security cards exactly)
- SSN or ITIN for you, your spouse, and dependents
- Dates of birth
- Filing status (Single, Married Filing Jointly, Married Filing Separately, Head of Household)
- Dependent relationship details
✈️ Travel Calendar & Addresses
Critical for reporting requirements and for determining eligibility for provisions such as the Foreign Earned Income Exclusion.
What you need:
- Dates of entry to and exit from the US and Luxembourg
- Workdays vs non-workdays (if tracking physical presence)
- All addresses during the tax year, with move-in and move-out dates
More information on maintaining a Travel Calendar
💼 Employment & Income Information
For Employees:
- Certificat de Salaire (Fiche de Retenue d’Impôt) (Wage Certificate with Tax Withholding) (Luxembourg equivalent of US W-2)
- Payslips (bulletins de paie/Gehaltsabrechnungen) from January to December showing cumulative totals
- Bonus, 13th month salary, or supplemental compensation statements (if any)
- Benefits documentation (meal vouchers, company car, etc.)
For Self-Employed / Freelancers (Indépendants):
- Déclaration d’Impôt (Tax Return)
- Records of gross income and expenses
- Invoices issued
- Home office details (if applicable)
- VAT records if registered
- Quarterly advance payment records (paiements anticipés)
Note for Self-Employed Individuals:
If you’re self-employed, you may need a Certificate of Coverage from the Ministry of Social Security to avoid paying US self-employment tax in addition to Luxembourg social security contributions. This certificate proves you pay social security and Medicare taxes to Luxembourg, making your self-employment income exempt from self-employment tax in the US under the US-Luxembourg totalization agreement. You can obtain it from:
- Ministère de la Sécurité Sociale
- For more information, visit the Social Security Administration’s international programs page.
Other Income:
- Interest and dividend statements (Luxembourg and US sources)
- Rental income and expenses
- Pension income
- Capital gains or losses
- Cryptocurrency transactions
Common mistake: Non-US income is still generally reportable on a US return.
🌍 Foreign Taxes Paid
Required to evaluate and calculate the Foreign Tax Credit.
What you need:
- Déclaration d’Impôt (Tax Return) (if filed)
- Certificat de Salaire (Fiche de Retenue d’Impôt) (Wage Certificate with Tax Withholding)
- Bulletin d’Impôt (Tax Assessment Notice) from ACD
- Tax payment receipts or bank statements showing payments to ACD
- Records of advance payments (paiements anticipés) if applicable
- Solidarity surcharge (contribution de dépendance) records
Important decision: Foreign Tax Credit, Foreign Earned Income Exclusion, or a combination. For most Luxembourg residents, Foreign Tax Credit provides better results due to Luxembourg tax rates, though this requires analysis of each individual specific situation.
Timing note: You can claim taxes paid or accrued. This choice affects which year’s Luxembourg taxes offset which year’s US taxes.
💰 Deductions & Credits
Common deductions:
- Foreign housing costs (rent, utilities, insurance)
- Student loan interest (US loans only)
- Retirement contributions (401k, IRA – Luxembourg pension contributions may have treaty benefits)
- Charitable contributions to US-qualified organizations (Luxembourg charities generally don’t qualify)
Common credits:
- Child Tax Credit / Credit for Other Dependents
- Foreign Tax Credit (Luxembourg income tax and solidarity surcharge)
- Education credits (if applicable for US institutions)
What you need:
- Receipts and supporting documentation
- Rental agreements (contrat de bail) and housing expense records
- Pension contribution statements (pension complementaire)
- Charitable donation receipts (verify US qualification)
🏦 Foreign Bank & Financial Accounts (FBAR)
An FBAR is required if the aggregate value of all foreign accounts exceeded $10,000 USD at any time during the year.
What you need for each account:
- Account number and IBAN
- Financial institution name and address
- Account type (compte courant, compte d’épargne, compte-titres, pension account)
- Maximum value during the year in EUR (converted to USD using Treasury rates)
Notes:
- Joint accounts and signature authority still count
- Complementary pension accounts (pension complémentaire) must be reported
- Investment accounts must be reported
- Business accounts where you have signing authority must be reported
More information on FBAR requirements
📊 Foreign Financial Assets (Form 8938)
Separate from FBAR, with higher thresholds and overlapping but distinct rules.
What you need:
- Bank and investment account details (similar to FBAR)
- Foreign stock or securities held outside accounts
- Luxembourg pension plan statements
- Foreign partnership interests
- Foreign-issued life insurance or annuities (assurance-vie)
More information on Form 8938 requirements
🏠 Foreign Rental Real Estate
What you need:
- Purchase date and price (in EUR and USD)
- Current fair market value
- Rental income and expenses (if applicable)
- Sale details (if sold): proceeds, adjusted cost base, capital gain calculation
- Mortgage and financing information
- Property registration documents (acte notarié)
- Property tax (impôt foncier) records
- Notary and registration fees
Reminder: US depreciation and capital gains rules differ from Luxembourg rules.
🇱🇺 Luxembourg Retirement Accounts & Social Security (Special Treatment)
Luxembourg retirement accounts have unique US tax treatment:
What you need:
- Annual pension contribution statements (pension complémentaire)
- Pension account balances (December 31)
- Social security contribution records (cotisations sociales)
- Pension distribution statements (if receiving payments)
- Employer pension scheme details
Key points:
- Luxembourg pension growth can be tax-deferred in the US if proper treaty elections are made
- Employee contributions may be deductible on US return under treaty provisions
- Employer contributions are generally not taxable income in the US
- Luxembourg state pension is taxable on both US and Luxembourg returns
- Social security contributions do NOT qualify for US tax credits
👶 Dependents & Education
For each dependent:
- SSN or ITIN
- Months lived with you
- Childcare provider details (name, address, tax ID)
- Education expense records (Form 1098-T from US institutions)
- International school tuition records
Note: Luxembourg or international school tuition does NOT qualify for US education credits in most cases.
🏥 Health Insurance
What you need:
- Proof of health insurance coverage (Caisse Nationale de Santé or private insurance)
- Private health insurance details (if applicable)
- Premium amounts paid
💳 Other Important Items
- Prior year US tax return
- IRS notices or correspondence
- Estimated tax payments made to IRS
- US state tax information (if you maintained state residency)
- Pension plan statements
- Numéro d’Identification (Luxembourg tax identification number)
- Residence permit documentation
- Record of any tax treaty elections made in prior years
✅ Ready to File?
Organizing these items upfront saves time and reduces the risk of missed reporting or penalties, even in years with little or no tax due. The US-Luxembourg tax relationship involves complex treaty provisions that require professional expertise, particularly given Luxembourg’s unique financial sector and cross-border employment situations.
🔎 Quick Reference
- Luxembourg Tax Year: January 1 – December 31
- Luxembourg Tax Filing Deadline: March 31 (extended to December 31 with tax advisor)
- US Tax Year: January 1 – December 31
- US Filing Deadline: June 15 (automatic extension for taxpayers abroad)
- Extended US Deadline: October 15 (with extension)
- FBAR Deadline: April 15 (automatic extension to October 15)
- USD/EUR conversion: Use Treasury Department rates or year-end rates consistently
Documents specific to Luxembourg:
- Certificat de Salaire (Fiche de Retenue d’Impôt) (Wage Certificate with Tax Withholding)
- Déclaration d’Impôt (Tax Return)
- Bulletin d’Impôt (Tax Assessment Notice)
- Bulletin de Paie (Payslip)
- Acte Notarié (Notarized Deed)
- Attestation de Cotisations Sociales (Social Security Contribution Certificate)
⚠️ Every individual income tax situation is unique and may involve nuances that are not obvious from general guidance. You should review your specific facts with a qualified tax professional before making filing decisions or taking action based on this information.
