Spouses married under separation of property own, jointly, the Paris town mansion that is their main home. The tax office raises the value declared for the wealth tax (impôt de solidarité sur la fortune, the French wealth tax replaced in 2018 by a property wealth tax); they claim a discount for joint ownership, each holding only a share, and contest the comparables. The Cour de cassation (the French supreme court for civil matters), on 27 March 2019, in a reported decision, dismissed: “the market value of a building is the price that could be obtained for it through the interplay of supply and demand on a real market, taking into account the factual and legal situation of the building at the taxable event”; and the court of appeal, “which, as it had to, assessed in concrete terms the possibilities of selling the building at issue, could deduce that the joint ownership of the property did not affect its value”. For the valuer, the ruling says two things: a discount is justified by a real constraint on the sale, not by an abstract legal status; and comparables described by weighted area, date, structure and surroundings are enough.
The facts
Two spouses married under separation of property bought together a town mansion in Paris, which they own jointly and which is their main home. The tax office considers that the value declared for the wealth tax for 2005 to 2008 must be raised and notifies a tax adjustment, based for each year on three sales of buildings in the same arrondissement, described by their address, year and building material, number of floors, presence of a terrace or garden and weighted developed floor area.
The taxpayers challenge this before the Paris court of appeal, which dismisses their claims on 6 November 2017. They appeal: the comparables allegedly ignore the state of repair, architectural quality and location; and the tax base should be the value of each spouse’s undivided share, not that of the building, which would justify an allowance.
The decision
The commercial chamber dismissed the appeal (Cass. com., 27 March 2019, no. 18-10.933, reported). On the comparables, it notes that the adjustment notice described the property “by presenting its location, its year of construction, its structure and the layout of the rooms, its weighted developed floor area, the calculation of which was detailed, the presence of a garden and its immediate surroundings”, and that the comparables specified “the address, the year, the building material, the number of floors, the presence of a terrace or garden and the weighted developed floor area”; the court of appeal, “which examined in concrete terms the comparables proposed by the tax office, could declare the procedure valid”.
On the discount: “the market value of a building is the price that could be obtained for it through the interplay of supply and demand on a real market, taking into account the factual and legal situation of the building at the taxable event”. The spouses bought the property together, their main home of which they are joint owners; they did not mention the joint ownership in their returns, and “it is unlikely that either of them would consider selling their share in this property”. The court of appeal, “which, as it had to, assessed in concrete terms the possibilities of selling the building at issue, could deduce that the joint ownership of the property did not affect its value”.
What this changes for valuation
The legal situation counts, but in concrete terms. The definition recalled by the Court is the valuer’s: a market price, taking into account the factual and legal situation of the property at the valuation date. Joint ownership is a legal situation; it weighs on value only if it weighs on the sale. Two spouses who bought their main home together and live in it will sell the whole building, together; no buyer will purchase an undivided share, and neither of them will sell one alone. A valuer who proposes a joint-ownership allowance must therefore show that the conceivable sale is that of a share, with the difficulties that implies: disagreement between co-owners, court-ordered auction, consent requirements. Otherwise the allowance is theoretical and the judge sets it aside. The glossary describes the décote and indivision.
Joint-ownership discount: no more for SCI shares. The article on SCI shares and the wealth tax shows the Court refusing, on 9 July 2025, a third “joint-ownership” discount to a partner who had already obtained two 10 % illiquidity discounts, the court of appeal having “rightly stated that the position of a partner in a property holding company is not that of a joint owner”. The two rulings point the same way: a discount pays for a real and specific constraint on the sale, and only once. The report names that constraint and checks that no allowance overlaps another, rather than applying a standard rate.
Described, weighted comparables from the same district. The ruling endorses a method: three sales per year, in the same arrondissement, described by their address, period and building material, number of floors, presence of a garden or terrace, and a weighted developed floor area computed under a stated rule. These are the criteria the French valuation charter requires for the comparison method, and which the valuer uses in a report for or against the tax office. The state of repair and architectural quality raised by the taxpayers are not ignored: they are dealt with by adjustments to the comparables, which the valuer quantifies and justifies, rather than by a wholesale rejection of the evidence. The article on comparables and the sale after death applies the same requirement to inheritance tax.
The main home: one statutory allowance, not two. The wealth tax, then the property wealth tax, grant a flat allowance on the main home, 30 % today. It already reflects the taxpayer’s occupation. Adding a joint-ownership discount between the occupying spouses would count the same constraint twice. A report valuing a main home for tax starts from the vacant market value, then applies the statutory allowance, without any other discount than those an external constraint justifies, such as an easement, a lease or proceedings.
Declare the exact situation. The spouses had not mentioned the joint ownership in their returns, which the ruling notes. A legal situation invoked after the event to reduce the value carries less weight than one declared from the outset and described in the valuation. The guide on the value to declare for your house under the property wealth tax describes the approach.
No discount in a partition either, for a different reason. The concrete assessment of the possibilities of sale answers the tax question: the price a third party would pay. Between co-heirs, that question does not arise. In a reported ruling of 22 June 2016 (Cass. 1re civ., no. 15-19.471), the Cour de cassation approved the refusal of any discount on jointly owned estate buildings burdened by a usufruct, since joint ownership and the split of ownership do not affect their market value “in the relations between the co-partitioners”. In partition accounts, buildings are therefore valued in full ownership, without a joint-ownership discount, whatever the possibilities of selling a share. The article on jointly owned property valued in full ownership in a partition develops the distinction.
What the valuer takes from it
- Market value is the price obtainable on a real market, taking into account the factual and legal situation of the property at the taxable event.
- A joint-ownership discount presupposes a real constraint on the sale; between spouses co-owning their main home, there is none.
- In 2025 the Court refused a joint-ownership discount to a partner in an SCI, who is not a joint owner: a discount requires a real constraint, described and counted only once.
- Comparables from the same district, described by date, structure, outbuildings and weighted area, form a valid basis; differences are handled by adjustments.
- The statutory allowance on the main home already reflects occupation; it does not stack with a discount for the same cause.
Further reading
The Market value page describes the assignment, its timescale and its fee. The guide French wealth tax: which value to declare for my house? and the glossary entries décote, indivision and méthode par comparaison complement this article. On the same theme: SCI shares and French wealth tax: two 10 % discounts, not three and French wealth tax: building land with environmental constraints. The decision is available on Légifrance.
What next
A declared value challenged by the tax office, comparables to discuss, a discount to justify?
I establish the market value of the property at the taxable date, with described and weighted comparables, and I justify each allowance from the actual possibilities of sale, for the reply to the tax adjustment or for the tax judge.
Free quote, by email or by phone. No commitment before the quote is accepted. Fees are never linked to the value of the property (Charte de l’expertise, Title I, §2.1).
