Personal taxation · Luxembourg
Before signing the pre-filled return: what to check
A pre-filled tax return must be checked before you sign it. Data supplied by the tax authority or imported by a software tool does not mean that your household's full situation and all relevant expenses are reflected. If the document is inaccurate or incomplete, consider which filing route is appropriate.
Financial Services Luxembourg · Licensed accountant · Head of the firm: Mickaël LOC. Editorial update: .
ACD simple tax return or software import?
The pre-filled simple tax return sent by the Luxembourg Inland Revenue (ACD) is an official scheme for eligible taxpayers. Software that imports certificates or carries over last year's data offers a different feature. The two situations must not be presented as the same document.
For 2025 income, the ACD announced that the pre-filled simple tax returns would be sent on 30 March 2026. Taxpayers must check the information before signing, or use another official route if a correction is needed.
The checklist table
| Item | Compare with | Discrepancy to look for |
|---|---|---|
| Year and persons | Document received and household situation | Wrong year, spouse or residence not updated |
| Salaries and pensions | Certificates from all payers | Omission, double import or correction not carried over |
| Withholding tax | Annual certificates | Withholding tax missing, duplicated or assigned to the wrong person |
| Foreign income | Supporting documents and tax treaty | Missing income needed to calculate the rate |
| Expenses | Certificates and rules for the year | Missing expense, cap or condition not checked |
| Validation | Chosen procedure | Draft mistaken for an actual submission |
Fictitious example: correct data, incomplete file
The pre-filled salary matches the certificate exactly. However, the taxpayer has bought a home and wants the mortgage interest reviewed. Checking the salary alone is therefore not enough to validate the choice of procedure or the deductions.
The review must compare the full situation with the scope of the document, then determine the appropriate form. It is not about randomly changing a field in the simplified document.
If you find an error
Do not sign information you know to be inaccurate. Gather the supporting documents and choose the appropriate filing channel with the tax office or a professional. If a return has already been submitted or a tax assessment notice exists, say so: the procedure is no longer the same.
Keep the document received, the corrected version, the supporting documents and proof of submission. No import method removes the need for this reconciliation.
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: 2025 income tax return campaign
- Guichet.lu: electronic filing and deadlines
- ACD: forms for individuals
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.