1948 Act tenancies: proving insufficient occupancy

Written by Guillaume Pouillier, CNAPS-licensed private detective, licence no. AGD 095-2024-03-06-20190240581 · Last updated: July 19, 2026

The French Act of 1 September 1948 created tenancies out of time: very low capped rents and a near-perpetual right to remain. But that exceptional right has a demanding counterpart: effective occupancy. Article 10 of the Act removes the protection where the beneficiary does not occupy the premises at least eight months a year, absent a legitimate reason (professional or health). Proving it, over time, is a job of methodical findings, our speciality, in particular demand in Paris where many such leases survive. This page explains what the Act requires, how occupancy is proven, over what period, and what the file is worth once complete, including the many cases that settle without ever reaching a courtroom, because a thirty-finding chronology leaves very little to argue about.

What does the 1948 Act say about occupancy?

The right to remain is reserved to those who effectively occupy the dwelling: article 10 of the Act removes it, notably, from an occupant who has not lived in the premises at least eight months per year, save legitimate reason. Insufficient occupancy is proven by all means, hence by findings.

The litigation turns on a question of fact: where does the occupant really live? An effective residence elsewhere (often a second home become the main one, or a move to a partner’s), a flat turned into a pied-à-terre, or organised under-occupancy for the benefit of relatives, each configuration strips the protection of its foundation.

The burden of proof lies on the landlord, and judges are demanding: vague neighbourhood attestations do not suffice. What is needed is a series of dated findings, spread over the relevant months, sketching an unambiguously deserted dwelling.

How do you prove a dwelling is not occupied?

By the methodical accumulation of convergent clues observed from public space: shutters and windows frozen, a letterbox overflowing or redirected, no comings and goings at living hours, no lighting in the evening, and the occupant’s presence observed… at his other address.

The “counter-residence” module often decides the case: establishing that the occupant lives elsewhere, with his habits, his vehicle, his daily life, answers the “extended trip” argument in advance.

Over what period must findings run?

The eight-month rule imposes proof built over time: a typical campaign spans three to six months, with regular but spaced passes, at varied hours, covering the key periods (back-to-school, holidays, deep winter). The long series is what separates proof from anecdote.

That is where amateurism fails: a landlord photographing closed shutters three times in January proves… three days of January. Our campaigns are designed with your lawyer to cover the reference period: randomised passes, a findings log, time-stamped photographs, and, where the configuration allows, correlation with durable clues (mail, vegetation, visible meters).

The final file presents a continuous chronology the occupant cannot explain by occasional absences, and the judge merely has to record what the facts say.

What happens to the lease once insufficiency is proven?

The right to remain falls: the landlord recovers free disposal of a property often immobilised for decades at a trifling rent. Depending on the case, the proceedings end in vacation of the premises or open a departure negotiation, which the findings file finally makes balanced.

The patrimonial stakes are considerable in Paris: a 1948 Act flat is valued far below its vacant value, and its rent sometimes does not even cover the charges. Exiting the regime changes everything, sale, re-letting at market conditions, recovery for a relative.

Many files also resolve without judgment: faced with a solid series of findings, the bad-faith occupant negotiates his departure rather than face a hearing lost in advance. The report then serves as transactional leverage, often the fastest and most economical outcome.

What if the dwelling is sublet or lent?

The 1948 Act also prohibits unauthorised subletting, and occupancy by third parties without right defeats the protection. Our findings then identify who actually occupies: rotations of visitors, stable occupants foreign to the lease, disguised rental listings.

The pattern is frequent: the protected occupant no longer lives there but “keeps” the flat for a child, a relative, or a discreet subtenant who pays a very real rent. These situations draw on our illegal subletting expertise: identification of the effective occupants, cross-checking with listings, chronology of rotations.

The report then articulates both grounds, insufficient personal occupancy and occupancy by third parties, handing your lawyer a double-action file.

Why is the campaign’s discretion decisive?

Because an alerted occupant simulates: a few conspicuous visits by the landlord, one question too many to the caretaker, and the flat suddenly “comes back to life”, lights on timers, weekly visits, mail collected. The campaign must remain invisible from the first finding to the last.

Our passes are unmarked, randomised and carried out by investigators nothing connects to the building. We formally advise the landlord against any parallel initiative during the campaign, threatening letters, questions to neighbours, “inspection” visits: each of those alerts can ruin months of findings.

The rule also applies to the judicial calendar: the summons only goes out once the file is complete. Showing your cards with a partial file gives the occupant time to rebuild an appearance of occupancy, and turns a won case into a debate of interpretation. Patience, here, is not caution: it is strategy.

Two typical files, anonymised

An occupant “in residence” since 1971, actually settled in the provinces for eight years, the flat serving as furniture storage; a 1948 Act three-room flat occupied by the official tenant’s nephew after she moved to a care home, unreported.

The storage flat. A landlord has suspected for years that his 1948 Act occupant lives elsewhere. A five-month campaign produces thirty-two findings without a single trace of life, a redirected letterbox, and an effective residence in the provinces, a village where the occupant is even active in local associations, open sources cited in support of every finding. The right to remain falls; the premises are vacated within the year, and a flat frozen since the seventies returns to the market at last.

The invisible nephew. An 89-year-old occupant moved to a care home; her nephew settled without right in the three-room flat at the 1948 rent. A short series of findings identifies the actual occupant, his working hours, his vehicle. Confronted with the file, the family returns the premises by settlement, without a hearing, without acrimony, and within weeks rather than years.

How much does it cost?

A 1948 Act campaign is billed at a flat fee by duration: findings fall under administrative enquiries (from €350 excl. VAT) for a short verification, while three-to-six-month campaigns get a written flat fee, passes at €85/hour (excl. VAT), degressive with volume. Free quote on sight of the situation.

Set that cost against the stakes: in Paris, the difference between a property immobilised under the 1948 Act and the same property vacant runs to hundreds of thousands of euros. The findings campaign is the investment that unlocks that value.

See the full price list.

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