Photo by Tara Winstead via PexelsThe marginal tax rate (TMI) is one of the most cited French tax indicators, and yet one of the most misunderstood. Many taxpayers know which bracket they fall into without always understanding what this rate really means, or how it applies to their income. Understanding your TMI makes it possible to assess the real benefit of a payment into a retirement savings plan, anticipate the tax impact of a bonus or exceptional income, and arbitrate between several investments with full knowledge of the facts.
What is the marginal tax rate (TMI)?
The marginal tax rate corresponds to the rate applied to the last bracket of taxable income, the one in which the household’s last euro falls. The French system is indeed based on a progressive scale: each income bracket is taxed at a different rate, rather than the entire income being taxed at a single rate.
Contrary to a widely held belief, reaching a bracket at 30, 41 or 45 percent does not mean that the household’s entire income is taxed at that rate. Only the fraction of income within that upper bracket is concerned. The lower fractions remain taxed at the lower rates that correspond to them.
The TMI therefore makes it possible to measure two things precisely: the tax cost of additional income (bonus, overtime, rental income) and the benefit generated by a tax deduction, such as a payment into a retirement savings plan.
How do you calculate your marginal tax rate in 2026?
Calculating the TMI takes two steps: determining net taxable income per tax unit, then locating that amount on the progressive scale in force.
The 2026 progressive scale: tax brackets
The scale applicable to income received in 2025 and declared in spring 2026 has five brackets:
| Fraction of taxable income per unit | Applicable rate |
|---|---|
| Up to 11,600 euros | 0 percent |
| From 11,601 to 29,579 euros | 11 percent |
| From 29,580 to 84,577 euros | 30 percent |
| From 84,578 to 181,917 euros | 41 percent |
| Beyond 181,917 euros | 45 percent |
This scale applies to net taxable income divided by the household’s number of tax units, never to the total undivided income. It is this division mechanism that explains why two households with the same overall income can have a different TMI depending on their family situation.
Worked example for a net taxable income of 40,000 euros
For a single person (1 tax unit) with a net taxable income of 40,000 euros:
- 0 percent bracket: 11,600 euros → 0 euro
- 11 percent bracket: from 11,601 to 29,579 euros, i.e. 17,979 euros → 1,977.69 euros
- 30 percent bracket: from 29,580 to 40,000 euros, i.e. 10,420 euros → 3,126 euros
- Tax due: 5,103.69 euros
The last euro of this income falls within the 30 percent bracket: this taxpayer’s TMI is therefore 30 percent, even though their actual average tax rate is only around 12.8 percent.
Marginal tax rate vs average tax rate: what is the difference?
The TMI and the average tax rate follow two different logics, and confusing the two is one of the most frequent mistakes in tax matters.
| Indicator | Definition | Purpose |
|---|---|---|
| Marginal rate (TMI) | Rate applied to the last income bracket | Measuring the impact of extra income or a deduction |
| Average rate | Ratio between total tax paid and net taxable income | Assessing the overall weight of income tax on the household |
In the previous example, the taxpayer shows a TMI of 30 percent but an average rate of around 12.8 percent, because only the last fraction of their income is taxed at the highest rate. For a wealth-related decision, such as assessing the benefit of a tax deduction, the TMI is always the relevant indicator, never the average rate. Both rates usually appear on the tax notice, in the tax calculation detail.
TMI vs withholding tax rate: avoiding the confusion
The withholding tax rate shown on payslips or pension statements corresponds neither to the TMI nor exactly to the average tax rate. This rate, calculated by the tax authorities from the latest known tax return, is used solely to determine the amount withheld each month from salaries, pensions or replacement income. It is an advance payment, not a final calculation of the tax due.
A gap between the withholding rate and the household’s real TMI is common, particularly when income changes during the year: a new job, exceptional income or a change in family situation. In that case, an adjustment takes place the following year when filing the tax return. The household may then owe an additional amount if withholding was insufficient, or receive a refund in the opposite case.
TMI and family quotient: the impact of family situation
The family quotient plays a decisive role in calculating the TMI, since the scale applies to income divided by the household’s number of tax units. A single person has one unit, a married or civil-partnership couple has two units, and each dependent child generally adds a half unit (a full unit from the third child onward).
Example: the impact of the family quotient on an income of 90,000 euros
For a net taxable income of 90,000 euros, family situation radically changes the applicable TMI:
- Single person (1 unit): income per unit of 90,000 euros, TMI of 41 percent, tax due of around 20,700 euros, an average rate close to 23 percent.
- Couple with two children (3 units): income per unit of 30,000 euros, TMI of only 30 percent, tax due of around 6,312 euros, an average rate close to 7 percent.
For an identical total income, the number of tax units thus shifts the TMI by a full bracket. This mechanism explains why a change in family situation (marriage, birth, divorce) should always be factored into tax or wealth planning.
What is the marginal tax rate used for in wealth decisions?
Knowing your TMI helps make informed decisions on several fronts:
- Estimate the real benefit of a tax deduction. A deductible payment of 1,000 euros into a retirement savings plan saves 300 euros in tax for a taxpayer with a TMI of 30 percent, versus 450 euros for a taxpayer with a TMI of 45 percent, for the same savings effort.
- Anticipate the impact of exceptional income. A bonus, overtime or a one-off capital gain can push a fraction of income into a higher bracket and increase the TMI applicable to it.
- Arbitrate between several savings vehicles. The choice between a retirement savings plan, life insurance or a PEA depends partly on the TMI, particularly when assessing the value of an upfront deduction.
- Choose between flat tax and progressive scale for taxing certain capital income, an option that is only advantageous if the household’s TMI is lower than the flat tax rate.
- Assess the tax benefit of a rental investment or a property tax relief scheme, whose advantage is usually calculated as a percentage of taxable income and therefore depends directly on the beneficiary household’s TMI.
How can you legally reduce your marginal tax rate?
The TMI depends directly on net taxable income per unit: reducing it means either lowering that taxable income through legal schemes, or increasing the household’s number of tax units.
- Pay into a retirement savings plan (PER) to benefit from a deduction from taxable income, within the annual available cap. See our full PER guide to understand how it works.
- Invest in tax relief schemes giving entitlement to a tax reduction or deduction, depending on your profile and investment horizon.
- Smooth exceptional income using the averaging mechanism provided by the tax authorities, which prevents a bonus or a one-off capital gain from pushing the entire income into a higher bracket.
- Review the full range of available tax relief solutions, detailed in our article on how to reduce your taxes in France.
For a full overview of the brackets and their annual revaluation, our article on the French income tax scale 2026 details the updated thresholds and their concrete impact on tax due.
Frequently asked questions
What is the marginal tax rate (TMI)?
The marginal tax rate is the rate applied to the last bracket of taxable income, that is, the rate that would apply to one extra euro of income. It is not the rate applied to the household's entire income, contrary to a common misconception.
How do you calculate your marginal tax rate in 2026?
The calculation divides the household's net taxable income by its number of tax units, then locates that per-unit amount on the 2026 progressive scale (0, 11, 30, 41 or 45 percent). The rate of the last bracket reached is the TMI.
Where can you find your TMI without calculating it yourself?
The marginal tax rate appears directly on the French tax notice, in the section detailing the tax calculation, next to the average tax rate.
Is the TMI the same for every member of a tax household?
Yes, the TMI is calculated at the level of the tax household as a whole, not individually. It depends on the household's total net taxable income divided by its number of tax units, regardless of how many people make up the household.
What is the difference between the TMI and the average tax rate?
The TMI only applies to the last bracket of income, while the average tax rate is the ratio between total tax paid and overall net taxable income. The average rate is always lower than or equal to the TMI.