Calculation of income tax: here is what changes for you in 2025

The income declaration, once signed, allows you to know the amount of your tax payable on your income affected in 2024. But how is your bill calculated? Our simulation to understand everything.

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The 2025 income declaration is officially open. Since April 10, you must verify your pre -filled income by the tax authorities in your online form on the tax site.gouv.fr, whether or not you are eligible for automatic declaration, or on your paper sheet received by post. And be careful to act in time: the deadlines for you to get rid of your tax obligations are this year set for May 22 for zone 1 (departments 1 to 19), on May 28 for zone 2 (departments 20 to 54) and June 5 for zone 3 (departments 55 to 974-976). After these deadlines, do you risk a sanction from the taxman in the form of an increase of 10% of the amount of the tax to be paid on your income affected in 2024. But how is your tax bill precisely calculated by the services of the Directorate General of Public Finances (DGFIP)? Explanations.

How to calculate the amount of your income tax in 2025?

At the end of the declarative campaign, the tax administration will calculate the amount of tax payable for each household. But it is possible now to estimate the amount of your tax. For this, there is a free simulatorset up by the Directorate General of Public Finances (DGFIP). Another solution is to carry out the calculation for yourself. It’s doable, but you have to proceed with method.

Simulation of your income tax calculation

Determine your global gross income

First step to calculate the amount of your income tax, you must determine your Global gross income. “It is equal to the sum of the income, profits and earnings that you have received in a calendar year”recalls Bercy. For this, you must add all of your income collected in 2024: net taxable salary, retirement pension, land income, industrial and commercial profits, real estate capital gain, etc. Without forgetting to apply a reduction on certain income, such as that of 10% for professional expenses (if you do not declare your professional costs to the real).

Example of calculation for a single person divorced

Example: To fully understand each step, Capital took the case of Martin. This 45 -year -old man is divorced. Apart from a taxable net salary of 40,000 euros per year, it has no other sources of income. Employee of a company, Martin chooses to use the flat -rate reduction of 10% for professional expenses. Thus, his global gross income is equal to 36,000 euros (40,000 euros – 4,000 euros).

Go from crude

Once the global gross income has been obtained, the second step is to calculate your overall net income. For go from crudethe formula is as follows: overall net income is equal to global gross income (the figure you have just obtained) less deductible charges. The main deductible charges are, for example, the food pensions paid to a minor or major child, a parent, or an ex-spouse, or the accommodation costs of an elderly person.

Example: divorced, Martin pays alimony of 200 euros each month to his daughter Pia, aged 15. This represents 2,400 euros per year. A sum he can deduct from his global gross income. Thus, his overall net income is equal to 33,600 euros (36,000 euros – 2,400 euros).

Transform your overall net income into net taxable income

Third step, you must transform your overall net income into Taxable net income. The taxable net income comes from the difference between your overall net income and any special abuses. For example, if your married or family in charge of family is attached to your tax household, you benefit from a reduction of 6,794 euros.

Example: In his case, Martin does not benefit from any special allowance.

Calculate your gross tax

Fourth step is the time to calculate your raw tax. And this is where the family quotient is involved. “THE family quotient designates the number of shares assigned to each tax household for the calculation of income taxspecifies Bercy. The objective is to adjust the amount of tax to the contributory capacity of each household (situation, family charges). ”

Example: We know that Martin is divorced. His daughter resides in exclusive custody with his mother. This situation only gives him the right to his own family quotient. Thus, its family quotient is as follows: 33,600 euros / 1 share = 33,600 euros. It is this sum that will be subject to the famous scale of income tax.

How to calculate your income tax rate in 2025?

Apply the scale of the tax revalued in 2025

The fifth step is to apply The income tax scale. It is divided into five sections to which a tax rate corresponds (0%, 11%, 30%, 41%and 45%). In 2025, the entry thresholds in these different marginal tax slices (TMI) were noted by 1.8% to take into account inflation.

Example: for Martin, Bercy will calculate the amount of his income tax From its net taxable income of 33,600 euros. In detail, up to 11,497 euros, there is no taxation (rate of 0%). On the other hand, beyond and up to 29,315 euros, the applied rate is 11%. Thus, 29,315 euros – 11,497 euros = 17,818 euros x 11% = 1,960 euros. Then, for the remaining fraction of the net taxable income of Martin, the tax rate is 30%. This gives 33,600 euros – 29,315 euros = 4,285 x 30% = 1,285.5 euros. It is then necessary to add 1,960 euros + 1,285.5 euros = 3,245.5 euros. Martin having only on the one hand of a family quotient, this figure is multiplied by 1. Thus, the gross income tax of Martin amounts to 3,245 euros.

Adjust the amount of the tax according to the ceilings of the family quotient, the discount and the tax advantages

At this stage, the amount of income tax is said to be “gross”, because it can still be adjusted according to certain parameters: caps of the effects of the family quotient, mechanism of the Decate for households with modest incometax reductions and credits, or contribution on high income.

Example: In 2024, Martin made a donation of 200 euros to Restos du Coeur, an association recognized organization for helping people in difficulty. This donation gives the right to a tax reduction of 75% within the limit of an amount paid of 1,000 euros. Thus, Martin benefits from 150 euros in tax reduction in 2025. This tax reduction will come to mining its gross tax amount: 3,245 euros – 150 euros = 3,095 euros. Ultimately, the amount of income tax that Martin will have to pay to the public treasury amounts to 3,095 euros.