An Unauthorized Sublease Is Valid Between the Parties

A sublease concluded in violation of Article L 145-31 of the Code de commerce — whether because it lacked the landlord's authorisation, or because the landlord was not called to participate in the deed — is not null and void. Between the tenant and the sub-tenant it produces all its normal effects for as long as the tenant retains possession of the premises. The sub-tenant can enforce the sublease against the tenant, pay the sublease rent, and occupy the premises. The irregularity affects the sublease's relationship with the landlord, not the contractual relationship between the two parties who signed it. The critical consequence is inopposability: the irregular sublease cannot be set against the landlord. No legal relationship exists between the landlord and the sub-tenant, and the sub-tenant has no rights against the landlord directly and cannot invoke the protections of the commercial lease statute vis-à-vis the landlord.

The Landlord's Remedies for Unauthorized Subletting

An irregular sublease gives the landlord three potential tools against the tenant. Judicial termination of the main lease — the irregular sublease constitutes a serious and legitimate breach. Once the sublease has been concluded without the participation formality, the breach cannot be remedied after the fact by a subsequent notification: it is an instantaneous infraction crystallised at the moment the sublease is signed. Refusal of renewal without eviction indemnity — the landlord can refuse renewal on the ground of the irregular sublease without paying the eviction indemnity (Art. L 145-17), regardless of whether it suffered any material prejudice. Recovery of all sub-rents — sub-rents are treated as civil fruits (fruits civils) belonging to the owner of the asset by accession under Articles 546 and 547 of the Civil Code. The Cour de cassation confirmed this principle in 2019 (n° 18-20.727) and again in 2023 (n° 20-20.141). The right extends to all sub-rents received, not merely those exceeding the main lease rent.

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The Clause Résolutoire

Where the main lease contains a clause résolutoire de plein droit, the irregular sublease may engage it. However, the clause can only take effect one month after a formal commandement requiring the breach to be remedied. The question arises whether the omission to call the landlord to the sublease deed can be remedied within that period. The answer is no: the failure to call is an instantaneous, irremediable breach. The one-month grace period has no practical effect. In the absence of a clause résolutoire, the landlord must obtain judicial termination by court proceedings.

The Sub-Tenant's Position

The sub-tenant who occupied under an irregular sublease is in a precarious legal position. It has no rights against the landlord and cannot invoke the protections of the commercial lease statute directly. Where the landlord terminates the main lease, that termination automatically extinguishes the sublease: the sub-tenant has no contractual relationship with the landlord to fall back on and becomes an occupier without legal title. The landlord cannot itself demand termination of the sublease — it is not a party to that contract — and cannot expel the sub-tenant directly while the main lease is intact (Cass. 3e Civ. 1-2-2012 n° 10-22.863). The sub-tenant also has no right to demand a fresh sublease renewal directly from the landlord in the case of a prohibited or irregular sublease (Art. L 145-32, al. 2).

Landlord Against Tenant
  • Judicial termination of main lease
  • Refusal of renewal without eviction indemnity (Art. L 145-17)
  • Recovery of all sub-rents as fruits civils
  • Can invoke clause résolutoire if applicable
Landlord Against Sub-Tenant
  • Cannot terminate the sublease directly (not a party to it)
  • Cannot expel sub-tenant while main lease continues
  • No legal relationship exists with irregular sub-tenant
  • Once main lease terminates: sub-tenant becomes occupier without title
Sub-Tenant Against Tenant
  • Sublease valid between parties while tenant has possession
  • If evicted due to tenant's fault: damages claim against tenant
  • Shared liability if sub-tenant failed to check formalities
  • No right to demand direct renewal from landlord

The Evicted Sub-Tenant's Damages Claim

Where the sub-tenant is evicted as a consequence of the irregular sublease — either because the main lease is terminated or because the landlord refuses renewal — it can claim damages from the tenant. The tenant failed in its obligation to ensure that the sub-tenant's occupation was regular and enforceable against the landlord. However, the sub-tenant's own conduct is relevant to the quantum of the claim. Courts have applied a principle of contributory fault: a sub-tenant who knew or should have known that the sublease was irregular and failed to take steps to regularise it — in particular, by demanding that the tenant call the landlord to the deed — has contributed to its own eviction. A shared liability of 50% has been assessed where the sub-tenant had access to the main lease, was aware that no participation formality had been completed, and nonetheless proceeded without insisting on regularisation. A damages claim requires an actual eviction: as long as occupation continues undisturbed, no recoverable loss has been suffered.

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Can an Irregular Sublease Be Confirmed?

An irregular sublease cannot be regularised retroactively by a subsequent call to the landlord: the failure to call is an instantaneous, irremediable breach. However, the landlord can choose to waive its right to invoke the irregularity, and this waiver can be express or tacit. The waiver must be unequivocal: mere knowledge of the sublease is never sufficient. The most reliable form is the landlord's express written confirmation that it accepts the sublease. Tacit waiver can be established from consistent conduct over time, but the threshold is high and the burden of proof lies with the party asserting the waiver.

The Consequences of an Irregular Sublease: Summary
An irregular sublease is not null between tenant and sub-tenant — it produces full effects for the duration of the main lease (Cass. 1978).
It is inopposable to the landlord: no legal relationship exists between the landlord and the sub-tenant under an irregular sublease.
The landlord can seek judicial termination of the main lease; the irregular sublease is a serious and legitimate ground (Art. L 145-17).
The landlord can refuse renewal of the main lease without paying eviction indemnity on the same ground — regardless of actual prejudice.
The landlord can recover all sub-rents received by the tenant as fruits civils belonging to the owner by accession (C. civ. Art. 546, 547; Cass. 2019, 2023).
The failure to call the landlord to the deed is an instantaneous, irremediable breach; the one-month grace period of the clause résolutoire has no practical effect.
The landlord cannot directly terminate the sublease or expel the sub-tenant while the main lease subsists (Cass. 1-2-2012).
The sub-tenant has no right to demand renewal directly from the landlord on an irregular sublease (Art. L 145-32 al. 2).
The evicted sub-tenant can claim damages from the tenant, subject to reduction for contributory fault if it knew of the irregularity and failed to insist on regularisation.
The landlord may waive the right to invoke the irregularity by unequivocal positive conduct; knowledge alone is never a waiver.
Dealing With Unauthorized Subletting of a French Commercial Lease?

Whether you are a landlord seeking to act on an irregular sublease, a tenant facing termination proceedings, or a sub-tenant whose position is at risk, the consequences require specialist legal analysis.

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This article is for general information and educational purposes only. It does not constitute legal advice. Always seek qualified legal advice before taking or responding to action on a sublease irregularity.