Joint or individual taxation: which should you choose?
Skimming?
We've prepared the shortcut for you.
In tax class 2, tax is calculated as if each person earned half of the couple's total income: this is known as splitting. The greater the wage gap, the more it reduces the overall tax. Pure individual taxation taxes each person on their own income in class 1: for equal incomes, it generally costs the same; for unequal incomes, it costs more. Its main purpose is to keep tax situations separate, not to lower your tax bill.
This is for you if
- You are married and a resident: joint taxation by default, individual taxation available upon joint request.
- You are in a civil partnership (PACS, Belgian legal cohabitation, or Luxembourg partnership): taxed individually by default, joint taxation upon request.
- You are a married cross-border worker: class 1 by default, taxed solely on your Luxembourg income; joint taxation requires tax assimilation (Article 157ter of the Income Tax Law, known as LIR, or the 50% rule for Belgian residents).
- Your couple is mixed resident / non-resident (one resident, one non-resident): joint taxation is possible upon joint request if the resident spouse personally earns at least 90% of the household's professional income in Luxembourg (Article 3, letter d LIR).
Not for you if you live as a couple without marriage or a registered partnership: joint taxation is strictly reserved for spouses and registered partners (Articles 3 and 3bis LIR).
Married couples or civil partners: two different rules
Married residents
- By default: joint taxation, tax class 2, from the year of marriage (Article 3 LIR).
- Upon joint request, since 2018: pure individual taxation (each in tax class 1 on their own income) or individual taxation with reallocation (the couple's income is combined then split, 50/50 unless requested otherwise, each in class 1).
- In case of disagreement between spouses, individual taxation is excluded (ACD).
Civil partners (PACS, legal cohabitation, Luxembourg partnership)
- By default: each person is taxed individually, in class 1, or in class 1a if they have a child qualifying for a child tax reduction.
- The tax card (the ACD document indicating your tax class to your employer) is not affected by the partnership: tax class 2 never appears on it solely because of a partnership (ACD).
- Upon joint request in Form 100 signed by both: joint taxation in class 2, or individual taxation with reallocation. A partnership existing from January 1 to December 31 and a shared home for the entire year are required.
- No need to request pure individual taxation: it is already the default regime for civil partners.
To understand the role of each tax class, read tax classes in Luxembourg.
Key figures to remember
| Item | Rule | Year |
|---|---|---|
| Married residents | Joint taxation (class 2) by default, pure individual or with reallocation upon request | Since 2018 |
| Civil partners | Taxed separately by default; joint or reallocation upon request, if partnership and shared residence span the full year | 2025 and 2026 |
| Deadline to choose | December 31 of the following year: December 31, 2026 for 2025 income | 2025 |
| Extra-professional allowance (amount deducted from taxable income when both spouses work) | €4,500 for the couple under joint taxation, €2,250 each under pure individual taxation | 2025 and 2026 |
| Form for withholding tax | Form 166 or MyGuichet.lu procedure, choice renewed automatically each year until revoked | 2026 |
| Consequence of a request | Mandatory tax return (Form 100), joint and signed by both | 2025 and 2026 |
How to make your choice
Married couples: for your tax withholding during the year
Joint request via the MyGuichet.lu procedure "application for simulation or individualisation / RTS rate", accessible without LuxTrust (Luxembourg digital identity) or eID and processed as a priority by the ACD, or Form 166 signed by both. RTS stands for tax withholding on salaries and wages (retenue d'impôt sur les traitements et salaires). The choice is carried over from year to year; a single signature is sufficient to revoke it.
Married couples: for the final tax assessment
The choice is confirmed in the tax return (a joint Form 100, signed by both, with income from each person), or selected directly in it, no later than December 31 of the following year. A request made before or during the year can be modified or revoked until that date; after that, it becomes irrevocable. Any request for individualisation (Form 166) makes filing a tax return mandatory, even after revocation.
Civil partners: in the tax return only
Nothing to do during the year. After the year ends, check joint taxation (or individual with reallocation) in Form 100 signed by both (box 312 of the 2025 Form 100 for residents; box 404 for non-residents, with the assimilation request in box 402), no later than December 31, 2026 for your 2025 income. For the first request: certificate from the Parquet général for a Luxembourg partnership, or an official foreign document (e.g. PACS certificate) covering the entire year.
Married cross-border workers
First tax assimilation, then the choice of taxation method, using Form 166 for tax withholding and Form 100 after the year ends. If you are unsure about the procedure, read tax return or annual adjustment.
A numerical example with two profiles
Two resident married couples, without children, both employed, 2025 income. Amounts: taxable income before the extra-professional allowance, tax calculated using the tax scale applicable since 2025 plus the 7% employment fund contribution, excluding tax credits.
Paul and Inès: €80,000 and €20,000
- Joint taxation: 100,000 - 4,500 = €95,500; tax class 2, so 2 × the tax on €47,750 = €13,132, i.e. €14,051 including the employment fund.
- Pure individual taxation, including the employment fund: Paul 80,000 - 2,250 = €77,750, i.e. €19,353; Inès 20,000 - 2,250 = €17,750, i.e. €411; total €19,764.
- Difference: joint taxation saves them €5,713 per year.
Lina and Hugo: €50,000 each
- Joint taxation: same base of €95,500, i.e. €14,051.
- Pure individual taxation: €47,750 each, i.e. approx. €7,026 each, €14,051 total (rounded).
- Difference: none.
Individual taxation with a 50/50 reallocation results, by design, in the exact same tax as joint taxation. To read these amounts, check the tax scale and marginal tax rate. At trigger, we notice that couples with highly unequal incomes lose the most when switching to pure individual taxation without doing the math beforehand.
Common mistakes
- Thinking that pure individual taxation is more advantageous when there is a large income gap: it is actually the opposite.
- Missing the December 31 deadline of the following year: the choice will no longer be considered, and a previous choice becomes irrevocable.
- Requesting joint taxation as civil partners after a separation or moving in together during the year: the conditions apply to the entire calendar year.
What might change
Bill No. 8676, introduced on January 6, 2026, provides in its initial draft for a single tax class "U" that would replace classes 1, 1a, and 2 starting from tax year 2028. People in classes 1 and 1a would transition automatically; couples already in class 2 could keep the current system during a 25-year transition period, with the option to switch to class U at any time, with no option to switch back (Chamber of Deputies, January 6, 2026).
As of October 9, 2026, this text is still under committee review and has not been passed: nothing changes for your 2025 and 2026 income.
Frequently asked questions
No. Civil partnerships are not recorded on tax cards, and tax class 2 does not appear on them for that reason. Joint taxation is only obtained after the year ends, through the tax return, if all eligibility conditions are met for the entire year.
Residents who get married during the year are taxed jointly for that year (Article 3 LIR), unless a joint request for individual taxation is submitted.
Yes, until December 31 of the year following the tax year in question, provided the request was made before or during that year. After that date, the choice becomes final for that tax year.