How LuxTaxTools calculates your 2028 tax

The formulas

• Class U (new article 118). Each partner is taxed alone. Scale: 0% up to €26,650, then 11%, 14%, 19%, 25%, 32%, 39%, 40% and 41%, and 42% above €234,800. Each rate applies only to the part of income inside its band.
• Tarif T (new article 118bis). The couple's taxable incomes are added and halved, the base scale behind today's class 1 is applied (0% up to €13,230, 42% above €234,870) and the result is doubled. This is the same as the article 118bis scale, whose bands are twice as wide (0% up to €26,460, 42% above €469,740), applied to the combined income.
• Employment fund surcharge. The tax is multiplied by 1.07. Above €150,000 for one person on Class U, or €300,000 for a couple on Tarif T, the calculator multiplies the whole tax by 1.09. The voted text (article 57) raises it to 109% only "pour la tranche du revenu imposable ajusté dépassant" those amounts, so above them our figure can be slightly too high. The break-even table and the worked examples stay below those amounts.
• Children under 3. The €5,400 early-childhood allowance per child is deducted on Class U only, €2,700 from each parent's income (split 50/50). The calculator gives no allowance on Tarif T.
• Verdict and break-even. The difference is Tarif T tax minus Class U tax, each rounded to the euro; the monthly figure is the yearly difference divided by 12. The break-even is the smallest share of household income for Partner B, tested from 0% to 50% in steps of 0.5 point, at which Class U costs less. The break-even table uses steps of 0.1 point.

Class U tax = Σ partners: scaleU(max(0, income − 2,700 × children under 3)) × 1.07
Tarif T tax = 2 × baseScale((income A + income B) ÷ 2) × 1.07

Every band of both scales, with worked examples, is in our Class U tax brackets guide.

What the calculator leaves out

• Tax credits: the employee tax credit (CIS), the single-parent tax credit (CIM), the social minimum wage tax credit (CISSM) and every other credit. They lower the tax you actually pay.
• Deductions: you enter taxable income, so deductions must already be taken out. The calculator does not work them out.
• Rounding by the tax office (ACD): official tables round income and tax in ways the calculator does not copy, so results can differ by a few euros.
• Non-residents and cross-border workers: assimilation rules are not modelled. The calculator is for residents.
• Indexation: under new article 125 the bands are multiplied by 1.1038 after the fourth index tranche counted from 1 January 2028. The calculator uses the starting values.
• Status of the law: Bill 8676 was adopted at first vote on 28 October 2026 (37 for, 11 against, 12 abstentions) and had not been published in the Journal officiel as of 2 November 2026. We update the formulas if the final law differs.

How we check the numbers

Every build of the site re-runs these checks and stops if one fails:

• Both scales are read from the voted text (PDF, articles 118 and 118bis) and must match the calculator rate for rate and band for band.
• Class U tax for one person must be within €3 of every row of the Ministry of Finance table attached to its answer to parliamentary question no. 4644 (11 September 2026) and of table 2 in the Finance Committee report (29 September 2026).
• The 2028 single-parent tax credit formula of the voted text and the 2026 formula published by the ACD must reproduce the ministry's credit figures.
• Every number quoted in the guides and on this site (for example €9,057 on Tarif T and €9,428 on Class U for a €60,000 / €20,000 couple) is recalculated and compared with the text.

The calculator comes out €1 a year above both official tables on every row where they show tax. We attribute this to rounding in the official tables, which the calculator does not reproduce.

Changelog

1. 2 Nov 2026: Methodology page and break-even table published; About, Contact and Privacy moved to their own pages; fonts now served from this site (privacy policy updated). No change to the formulas.
2. 2 Nov 2026: Guide on the end of class 1a. Calculator Class U figures checked against the Ministry of Finance table (parliamentary question 4644) and the Finance Committee report: within €1 on every row.
3. 31 Oct 2026: First guides published. Wording aligned with the text adopted by the Chamber at first vote on 28 October 2026 (37-11-12). Class U and Tarif T scales parsed from the voted text: identical to the calculator, so no change to the figures.
4. 30 Oct 2026: Separate English, French and German pages (/, /fr/, /de/). Privacy policy updated for cookieless Cloudflare Web Analytics.
5. 28 Oct 2026: First version of the calculator, based on Bill 8676 as debated in the Chamber of Deputies that day.

Sources

1. Chamber of Deputies: text of Bill 8676 as adopted on 28 October 2026 (PDF, French)
2. Chamber of Deputies: parliamentary file 8676 (status, votes, opinions)
3. Minister of Finance: answer of 11 September 2026 to parliamentary question no. 4644, single-parent tax burden 2024, 2026 and 2028 (PDF, French)
4. Chamber of Deputies: Finance Committee report on Bill 8676, 29 September 2026 (PDF, French), table 2 on class 1a
5. ACD (tax administration): single-parent tax credit (CIM) from tax year 2025
6. ACD (tax administration): tax classes of resident taxpayers (current rules, who is in class 1a)