For the past few years, your tax return has looked like a form already half-filled out by someone else. Salaries, pensions, dividends: all this data is in fact transmitted directly to the tax administration by your employer, your bank or your broker, or even your pension fund. It is then very tempting to just validate without rereading carefully, especially when everything seems in order. Except it could actually cost you…
Because the taxman doesn’t know your whole life. He doesn’t know that you paid a pension to your ex-spouse, that your child worked this summer, or that you hold an account in a European neobank. Maître Noël Dalus, lawyer at Avocats Picovschi, sees them regularly: “A question that often comes up concerns form 3916 on undeclared foreign accounts, it is an important part of the regularizations that we have been able to make. There are taxpayers who forget an account with a neobank, forgetting that it had to be declaredor others who are in good faith, particularly after a death: they become co-holders of an account abroad without knowing it. » And in the event of a tax audit, if this account is discovered, it can cost between 1,500 euros per account and per non-prescribed yearand even 10,000 euros if it is opened in a State which has not concluded an agreement with France to combat tax fraud.
When your personal life escapes the tax authorities
Family situations are the first blind spot in the declaration. If you are a single parent (single, divorced or separated, raising one or more children alone without shared custody), box T entitles you to an additional half-share. Another half share may apply in the event of widowhood, or if you or one of the members of your household is recognized as 40% or more disabled. The administration never checks these boxes for you. Maître Noël Dalus sums it up bluntly: “It’s a real subject, the family situation, because people make mistakes, and it’s sometimes really to their disadvantage. »
Likewise, the tax authorities never pre-fill box 1AO, which lists alimony payments received from a parent or ex-spouse. If you receive one, it is still taxable for this year and must be declared manually. Conversely, the pensions you paid last year are deductible (boxes 6GU, 6EL or 6EM). Because it should be noted that from next year, these rules will be reversed by the 2026 finance law: the parent who pays will no longer be able to deduct these amounts, and the one who receives them will be exempt up to 4,000 euros per child.
For adult children attached to your household, their internship or employment income is entered in boxes 1CJ and 1DJ. Maître Noël Dalus insists: “If they worked three months in the summer and earned significant income, we must not forget to declare it. » There is, however, one exception: students benefit from an exemption on the first 5,405 euros won in 2025.
Also think about box 1AK for your real professional costs if they are important, in box 7GA for childcare costs of a child under 6 years old, and to tuition discounts often forgotten: 61 euros per middle school student (box 7EA), 153 euros per high school student (box 7EC), 183 euros per student (box 7EF).
Rental and capital income, not to be neglected
On the rental income side, the tax authorities do not intervene either. In micro-land tenure regime (bare rental, income less than 15,000 euros), you must report your rents in box 4BE. For furnished rental via Airbnb or a similar platform, refer to the section “Income from non-professional furnished rentals” of your statement. Finally, if you are in real land tenure and your charges exceed your rents, you can deduct this deficit from your overall income up to 10,700 euros per year.
Likewise, on capital income, box 2OP can be confusing. By default, your dividends and interest are taxed at 30% via flat tax. Check the 2OP box allows you to switch to the progressive income tax scale, which is advantageous if you are in the 0 or 11% marginal tax brackets. But Maître Noël Dalus recommends not checking it without thinking: “When you have modest income, yes, it is better to check it. But when you have significant income, it is better to abstain ». And he warns: “Mistake in this direction can be costly. » Because from a marginal tax bracket of 30%, the progressive scale will cost you more than the flat tax.
High wealth: the declarations that no one will make for you
If the net value of your real estate assets exceeds 1.3 million euros (after deduction of real estate loans and 30% reduction on the main residence), you are liable for real estate wealth tax. The IFI declaration is not automatic : it is up to you to complete it in your tax return, without waiting for a letter from the tax authorities. Many taxpayers are unaware of this during the first year when their assets cross the threshold. And for high incomes, there is also exceptional contribution on high incomes (CEHR): it applies from 250,000 euros of reference tax income for a single person (500,000 euros for a couple), to be declared on form 2042 C.
Did you make a mistake? A corrective declaration is possible on impots.gouv.fr throughout the duration of the declaration campaign. After this period, a claim remains possible until December 31 of the second year following the collection of the tax. Master Noël Dalus nuance, however: “If rectification is always possible, it depends on the type of error: for example, for the PFU, it’s complicated. »
