A buyer discovers, after completion, what the seller kept quiet: a neighbour whose behaviour makes the building unliveable, a past insurance claim, a project, an easement. The buyer does not want to hand the flat back; they want to pay the right price. Until now, some courts granted only a lost chance of having negotiated a better price, reduced by a probability factor. The reported decision of the Third Civil Chamber of the Cour de cassation (the French supreme court for civil matters) of 28 May 2026 settles the point: a buyer who is the victim of fraud (dol) and keeps the property may claim compensation for an excess price. For the valuer, that changes what has to be measured.
The facts
By deeds of 5 and 6 April 2011, a couple bought a flat and a parking space for €615,000. On 13 April 2016 they resold them for €710,000 to new buyers. The new buyers then complained of the abnormal behaviour of the occupant of the neighbouring flat and sued their sellers for damages on the ground of fraud, without seeking annulment of the sale.
On 12 July 2024 the Paris Court of Appeal found fraud and held that the buyers’ loss corresponded to the depreciation of the flat’s value caused by the insecurity linked to the neighbour; it assessed that discount at 15% of the sale price, €106,500, and ordered the sellers to pay jointly. The sellers appealed: a victim of fraud who does not seek annulment can only recover a lost chance of having contracted on better terms, and a lost chance can never equal the hoped-for advantage.
The decision
The Cour de cassation dismissed the appeals (Cass. 3e civ., 28 May 2026, appeals no. 24-20.821 and 24-20.944, reported).
It held, under former articles 1116 and 1382 of the French Civil Code applicable to the case, that “the buyer of a property, victim of fraud, who has chosen not to seek annulment of the contract of sale, may bring an action for compensation for an excess price” (translated from the French). It then approved the lower court: “having found that the loss suffered by the buyers corresponded to the depreciation of the flat’s value caused by the insecurity resulting from the neighbour’s behaviour, the Court of Appeal assessed it, within its own power, at 15% of the purchase price”.
The loss is therefore not the lost chance to negotiate: it is the gap between the price paid and the value of the property as it is. The solution holds under the current texts, which kept fraud (article 1137) and non-contractual liability (article 1240).
What this changes for the valuation
A discount is measured, not a probability. Under the lost-chance reasoning, the report had to estimate a hypothetical price reduction and then weight it by the probability that the seller would have accepted it, which often produced small and poorly reasoned figures. The excess price is measured like an ordinary loss of value: market value of the property at the date of the sale without the concealed element, market value with it, difference. The method is comparison, adjusted for the element in question (Charte de l’expertise en évaluation immobilière, the French property valuation charter, 6th edition, November 2025, Title III, ch. 2), at the same valuation date as the sale.
The percentage must be justified. The Court of Appeal retained 15%. That figure lies within its own power, but it convinces only if it rests on something: sales of comparable properties affected by a neighbourhood nuisance or a degraded environment, longer marketing periods, the cost of measures the buyer will have to take, evidence that the nuisance persists. A report that states “15%” without references exposes the party to a dispute over the amount, even if the principle is settled.
The price paid is the reference, not an automatic ceiling. The buyers paid €710,000 for a property their sellers had bought for €615,000 five years earlier; that gap is the market, not the fraud. The excess price is assessed against the value of the property on the day of the sale, as an informed buyer would have paid it, not against the earlier purchase price.
The same reasoning for other concealments. An undeclared subsidence claim, recurring damp, a known nuisance, pending proceedings with the co-ownership, a neighbouring building project: whenever the buyer chooses to keep the property, the report quantifies the excess price. When the buyer chooses annulment, the heads are different, restitutions on one side and damages on the other, as another decision of January 2026 on noise nuisance recalls.
What the expert takes from it
- The deceived buyer can keep the property and claim the excess price; they are no longer limited to a lost chance.
- The excess price is a loss of value at the date of the sale: value without the concealed element, value with it, difference, by comparison.
- The percentage retained must be supported by references; a settled principle does not dispense with justifying the amount.
- The seller’s earlier purchase price is not the measure of the loss; the market value on the day of the sale is.
- The report must say clearly whether it quantifies an excess price (property kept) or restitutions and losses (sale annulled): the methods differ.
Further reading
The Property loss of value page describes the assignment, its timescale and its fee. The guide I paid too much: can I challenge the price? and the glossary entries moins-value and valeur vénale complement this article. On the same theme: Sale annulled for noise: a lost capital gain must be certain and Cancelling a property sale in France: serious price, lesion, fraud. The decision is available on Légifrance.
What next
Did the seller hide something that weighs on the value?
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