You are buying a property together as an unmarried couple — cohabiting partners, or in a PACS without a specific property regime — and you want your partner to keep the home if you die. Without a specific arrangement, the situation can be devastating: the deceased’s share enters their estate, and their legal heirs — children from a previous relationship, parents, siblings — can claim their portion. The survivor may be forced into unwanted co-ownership with strangers, unable to buy out their share.

The tontine clause — legally known as a clause d’accroissement — is one of the most elegant solutions to this problem. Little used and often misunderstood, it deserves careful consideration before any joint acquisition in France.

The tontine takes its name from Lorenzo Tonti, a Neapolitan financier who invented a collective lending scheme in the 17th century whereby interest payments flowed to survivors until the last one remained. Applied to real estate, the logic is similar: by inserting an accroissement clause into the notarised purchase deed, both co-buyers stipulate that the survivor shall be deemed to have been the sole and exclusive owner from the very outset of the acquisition.

This is not a gift or a bequest. It is a mutual conditional purchase: each party buys the entire property subject to the condition of surviving the other. At the death of the first party, the survivor’s ownership right « crystallises » retroactively — as if the other had never been a party to the deed. No probate proceedings are required for the property concerned.

In practice, the clause must appear in the authentic deed of sale, drafted by the notaire with precision. It cannot be added retrospectively to a property already held in indivision — except by selling and repurchasing, which generates costs and specific tax consequences. This is why the tontine must be planned from the outset, at the acquisition project stage.

The tontine’s primary benefit is fiscal. Under ordinary law, an unmarried partner who inherits from their non-PACS partner is subject to French inheritance tax at a rate of 60% (after a negligible allowance of €1,594). For a flat worth €800,000 of which the deceased held a 50% share, the tax cost can exceed €230,000 — often impossible for the survivor to fund.

The tontine circumvents this punitive regime. Pursuant to Article 754A of the French General Tax Code (CGI), the acquisition of the deceased’s share by the survivor under a clause d’accroissement is subject to droits de mutation à titre onéreux (transfer duties), just like an ordinary sale. The applicable rate is that of standard property transfers, approximately 3.80% on the net value of the acquired share — compared with 60% in the absence of a tontine. The saving is substantial.

That said, where a PACS with a will provides complete inheritance tax exemption for the surviving partner, the tontine remains superior in situations where the PACS is refused (personal or administrative reasons, or foreign non-resident partners) or where life insurance cannot absorb the full value of the property.

The tontine is not a mechanism to use without careful preparation. To be valid and produce its favourable tax effects, it must satisfy several cumulative conditions.

Genuine uncertainty about survival

The fundamental condition is the existence of a genuine alea at the time of signing. Both parties must present sufficiently comparable life expectancies for each to have a reasonable prospect of surviving the other. In practice, a significant age gap — beyond twenty to twenty-five years, according to established case law — may lead the French tax authority to recharacterise the tontine as a concealed gift, triggering inheritance tax treatment.

Similarly, if one co-buyer is seriously ill at the time of purchase, the alea is absent and the clause risks being voided. The Cour de cassation has maintained a consistent position on this point since its ruling of 22 November 2005.

Proportionality of contributions

Each party’s contributions must be proportional to their ownership share in the deed. If one contributes 90% of the price and the other 10%, but the deed stipulates 50/50 ownership, the tax authority may treat part of the arrangement as a gift, taxable accordingly. The respective contributions — personal equity, mortgage share — must be carefully calibrated to match the stated percentages.

Precise notarial drafting

The clause must be drafted by the notaire with extreme precision. Any ambiguity as to its nature, its effects, or its reciprocal character may compromise its enforceability against the tax authority or third parties. A notaire specialising in patrimonial law is essential.

The tontine presents significant practical constraints that may make it unsuitable for certain situations.

These limitations make the tontine a complementary tool, to be integrated within a broader wealth strategy — not a substitute for other protection mechanisms. It naturally combines with a will, a life insurance policy with a designated beneficiary, and, where applicable, a PACS or marriage contract.

In practice, the tontine suits a specific profile. It is particularly well-adapted for unmarried cohabiting couples — notably international couples residing on the Côte d’Azur — who wish to purchase a primary residence or holiday home together without formalising their relationship through a PACS or marriage. It also works well for partners of similar age, with comparable financial contributions, and a clear intention to prioritise the survivor over other heirs.

Conversely, the tontine is less appropriate when there is a significant age gap, when one partner has children from a previous relationship whose rights must be preserved, or when the property’s liquidity is a near-term imperative (likely sale within five to ten years).

For married couples, the tontine is generally redundant: the standard community of property regime already protects the surviving spouse, and the full inheritance tax exemption between spouses (TEPA Act, 2007) makes the tontine’s tax benefit negligible. The mechanism is designed for those whom ordinary succession law leaves without protection.

* Life insurance covers the capital subscribed, not the real estate value itself. A combination of tools is often the most robust approach.

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