Personal taxation · Luxembourg
Tax card, Form 164 or 166: which procedure?
Form 164 relates in particular to the tax withholding card for the current year. Form 166 is used for certain requests by married taxpayers for individualisation or for an RTS (wage tax) rate. Forms 163 and 100 concern the adjustment or the annual assessment: they are not interchangeable.
Financial Services Luxembourg · Licensed accountant · Head of the firm: Mickaël LOC. Editorial update: .
Choose the form according to your objective
| Objective | Route to consider | What it does not replace |
|---|---|---|
| Error or reduction on the card | Form 164 and RTS office | Annual review of the file |
| Couple option / RTS rate | Official procedure or Form 166 | Full analysis of options and obligations |
| Adjustment of withholdings | Form 163 if the conditions are met | Form 100 required or chosen under the rules |
| Assessment by tax return | Form 100 | Necessary update of a card during the year |
A card can remain valid for several years
Tax withholding cards have been multi-year since 2023 and are therefore not systematically reissued every year. Some updates are made automatically after a change known to the tax authorities; other corrections or reductions require the taxpayer to take the initiative.
Check the address, employments, tax class and deductions shown. The administrative validity of the card does not prove that all of the year's expenses have been brought to the attention of the ACD.
A withholding rate is not the final annual rate
An additional card may show a flat rate. It should not be read as the single rate that will definitively determine all of the household's income. The withholding is reconciled with the annual tax when the applicable procedure is carried out.
Fictitious example: updating a card reduces the withholding for the following months. That does not mean an equivalent refund for past months, nor that no balance will be due on the return.
Documents and checks
- Card currently in force and its validity date.
- Evidence of the change or of the expense claimed.
- Certificates and income of the couple required by the request.
- Form for the correct year and the exact RTS office addressee.
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: deductions and Forms 100, 163, 164
- ACD: forms for individuals
- ACD: questions from 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.