2025 Tax Return: Key Points to Keep in Mind Before the Online Service Opens

The online tax filing service will open on April 9, 2026. Between a delayed budget bill, the increase in the CSG tax on investment income, and the new rules on furnished rentals, there are several issues that deserve to be addressed in advance to avoid unpleasant surprises.
 

Every spring brings its share of forms, checkboxes, and questions left unanswered until the last minute. The 2026 tax filing season, covering 2025 income, will be no exception. The online filing service will open on April 9, with three deadlines staggered according to the taxpayer’s department of residence. While the 2026 Finance Act—which was passed very late—did not drastically alter the tax structure, several technical and regulatory changes make it advisable to get a head start this year.
 

The first step is to review your family situation. A death that occurred in 2025, a return from abroad, or a change in marital status: each of these events affects your tax status and must be properly reported. The question of whether to include adult children in the tax household is also worth considering each year. Depending on the household’s income and the child’s income, including them may be advantageous or, conversely, disadvantageous. A comparative calculation between including them and filing separately—taking into account any child support payments—will help you decide.
 

Another point to note: income from financial assets. The recent increase in the CSG has changed the overall social security tax burden on dividends, interest, and capital gains. Taxpayers who have opted for the progressive tax scale rather than the 30% flat-rate withholding tax should recalculate their figures, as the trade-off between the two options may have changed.
 

Furnished Rentals and Foreign Bank Accounts: Two Topics Not to Be Overlooked
The Le Meur Act, which amended the tax regime for non-professional furnished rentals, is having its first impact on the 2025 income tax return. Affected landlords should review the new tax rules applicable to their rental income, particularly regarding the thresholds and deductions under the micro-BIC regime. These adjustments may have significant implications for the amount of tax owed.
 

Furthermore, the requirement to report bank accounts held abroad remains a sensitive issue. Any account opened, used, or closed abroad during the year must be included on the tax return, or else face penalties of up to 1,500 euros per undeclared account. With the tax authorities’ enhanced digital tools and the automatic exchange of information between countries, the risks associated with an omission—even an unintentional one—are becoming increasingly real.
 

Finally, as Laurent Desmoulière and Elise Moras of Meeschaert’s wealth management division point out, taxpayers who have not filed the required return by the end of December 2025 for the differential tax on high incomes must bring their situation into compliance. This measure, which establishes a minimum tax rate of 20% for the wealthiest households, should not be overlooked.
 

IFI and Real Estate Holding Companies: Decisions to Prepare
With regard to the real estate wealth tax—whose filing has been integrated into the income tax return for several years now—the valuation of real estate assets as of January 1, 2026, is the key task. Discounts may be applied in certain cases—such as when the property is used as a primary residence, in cases of joint ownership, or where leases are in effect—but they must be justified and consistent with market realities. IFI reduction measures, particularly donations to certain public-interest organizations, remain available and should be factored into planning well in advance.
 

For owners of estate holding companies, a new issue has arisen this year: the prospect of a tax related to holding assets for personal use within these structures. It may be necessary to make adjustments, and it is advisable to prepare for this with the help of a specialized advisor rather than discovering the issue when filing the tax return.