Cross-border worker tax return in Luxembourg

An engagement tailored to your household

The first check concerns tax residence and the year in question. We then identify the salaries, pensions, rental income and other income of the taxpayer and, where the calculation requires it, of the spouse. The treatment depends on the type of income and the applicable tax treaty.

Assimilation to resident taxpayers can open up provisions available to residents, but it also involves a calculation that includes foreign income to determine the tax rate. Being eligible therefore does not automatically mean a saving.

The processing steps

• Assessment of residence, income and the filing obligation.
• Review of the conditions for assimilation and of the relevant household options.
• Reconciliation of certificates, withholding tax and supporting documents; explanation of the assumptions.
• Preparation of Form 100 and the necessary appendices; filing if the engagement provides for it.
• Review of the tax assessment notice and follow-up within the scope of the quote.

France, Belgium and Germany: the differences to keep in mind

The country of residence affects the tax treaty, the foreign formalities and certain assimilation conditions. For a Belgian resident, in particular, the route based on the household's professional income must be distinguished from the standard individual test.

Days worked outside Luxembourg and business trips must be documented. Taxation and social security affiliation follow different rules. A social security tolerance does not replace a tax analysis.

What must be confirmed separately

The Luxembourg engagement does not automatically include preparing a French, Belgian or German tax return. We specify the coordination needed and the professional responsible for each formality.

Prepare the annual certificates and the record of days worked per country. Send documents only through the channel agreed after first contact.

The firm’s other tax engagements

Depending on your situation, the firm also handles tax, VAT and payroll, the regularisation of late tax filings and assistance during a tax audit. Fees are listed in the firm’s fee grid.

Official sources and scope

• ACD: assessment based on a tax return
• ACD: assimilation to residents, article 157ter
• ACD: questions from non-resident taxpayers

The rules apply to the year and profile concerned. Examples flagged as fictitious explain a method; they are not an individual validation. The documents and options of your file are covered by a separate engagement.

Your next step

• Non-resident tax assimilation in Luxembourg: conditions
• Foreign income in Luxembourg: tax return and global rate