LMNP and SIRET: mandatory or not, and how to obtain it in 2026?

LMNP (loueur en meublé non professionnel), France's non-professional furnished rental status, is one of the most common real-estate structures for private landlords. A question comes up almost universally in the early weeks after a furnished acquisition: is a SIRET number (the French business registration identifier assigned by INSEE) actually required?

The answer from the DGFiP, France's tax authority, is unambiguous: yes, a SIRET is mandatory, and the registration must be completed within 15 days of the first rental. The regime you choose for taxation, whether the simplified micro-BIC flat-rate system or the full réel regime with depreciation, does not change this obligation.

Direct answer: a SIRET is mandatory in LMNP. The declaration of activity start must be filed on the INPI single-entry portal (formalites.entreprises.gouv.fr) within 15 days of the first day of rental. This applies to micro-BIC and réel regime landlords alike.

Yes. From the moment you start renting out a furnished property, even a single studio, even at modest rent, you are carrying out a commercial activity under French tax law (BIC, bénéfices industriels et commerciaux). That activity must be formally registered.

The start-of-activity declaration automatically generates a SIRET number, issued by INSEE. That number identifies your activity with the DGFiP, with the local tax office handling CFE (cotisation foncière des entreprises, a local business tax), and where applicable with your professional online space on the DGFiP website.

LMNP status is a tax qualification, not an administrative exemption. Being classified as non-professional does not mean being unregistered.

What the DGFiP specifies#

The guidance published on impots.gouv.fr states that any furnished landlord, professional or non-professional, must declare the start of activity within 15 days of the first rental day. Since 2023, this formality is completed online via the INPI single-entry portal. The old P0i paper form is no longer the reference channel for new registrations.

Source: impots.gouv.fr — Furnished rentals.

Step-by-step procedure#

1. Create an account on formalites.entreprises.gouv.fr (also reachable via procedures.inpi.fr) using your personal email address.
2. Select the formality type: start of activity as a non-professional furnished landlord.
3. Enter the exact start date of the rental, not the purchase date of the property, not the signing of the preliminary sale agreement.
4. Provide the full address of the rental property, your full personal details, and your chosen tax regime (micro-BIC or réel simplifié).
5. Submit the declaration. The INPI forwards the file to the DGFiP and INSEE.
6. Receive your SIRET number by email, typically within 15 working days from submission.

Documents to have ready#

If the property is held through a company (SCI, SARL de famille, etc.), the registration process is different: the company, not the individual, holds the SIRET. That situation warrants specific professional guidance.

Timeline and practical note#

The 15-day deadline runs from the first actual day of rental, the date your first tenant takes possession. A declaration filed before the property is let is technically early; it remains permissible in practice, but the start date entered must remain consistent with the reality of the rental.

For a straightforward file, the online form takes 20 to 30 minutes to complete. Processing time before receiving the SIRET can reach three weeks during peak periods.

The absence of a declaration does not automatically trigger a clearly quantified financial penalty for LMNP landlords. Drawing comfort from that would be a mistake. The consequences are real, even if they manifest indirectly.

Identified risks#

On the CFE: the cotisation foncière des entreprises is due by any furnished landlord from the first year of activity, subject to applicable exemptions. Without a SIRET, the local tax office cannot link your activity to a coherent CFE file. CFE assessments may fail to reach you, which does not extinguish the liability. Late interest and surcharges may apply if a regularisation is triggered.

On the annual tax package (liasse fiscale): under the réel regime, the liasse fiscale (forms 2031 and 2033) is filed against your activity as identified by its SIRET. A missing or incorrectly referenced SIRET can block or delay electronic filing.

On the DGFiP professional online space: certain digital exchanges with the tax authority (CFE notices, filing acknowledgements) require an active professional space linked to a valid SIRET.

On late regularisation: the DGFiP may challenge the start-of-activity date you declare on regularisation, which affects depreciation entitlements, the deductible expense period, and the capital gains calculation at the time of sale.

A worked example#

A landlord starts renting a furnished flat on 1 March 2026 and omits the start-of-activity declaration. In September 2026, when preparing the 2042 C Pro income tax return, the adviser identifies the missing SIRET. Regularisation is possible, but requires reconstructing the start date using contemporaneous evidence: the lease, the first rental receipts, utility invoices. If the date entered on regularisation does not match the documents, the deductibility of expenses and the depreciation starting point (under the réel regime) may be challenged in a tax audit.

By contrast: a landlord who files the declaration within 15 days has a clean file from the outset, no reconstruction to carry out, and can prepare the annual return without administrative friction.

This is one of the most frequently asked questions, and the answer is nuanced but largely straightforward.

As a general rule, one SIRET is sufficient for multiple furnished properties held in your own name. The SIRET identifies you as an individual engaged in furnished rental activity, it does not attach to each individual property. You are a single economic entity exercising a furnished rental activity, regardless of how many units are involved.

Key exceptions to know#

Confusing your personal SIRET with a company's SIRET is a classic operational error, particularly when switching to the réel regime or carrying out a restructuring.

For more on the tax implications of LMNP, see our article LMNP taxation in France.

The registration requirement is identical under both regimes. What changes is what the SIRET is used for downstream.

Switching from micro-BIC to the réel regime does not require a new registration. It is a tax option exercised with the DGFiP before 1 February of the relevant year. Your SIRET remains unchanged.

For what this transition involves in practice, read our article Choosing an accountant for LMNP réel regime.

The CFE is a local business tax levied on furnished landlords, subject to specific exemptions. It is administered by the local tax office (SIE) with jurisdiction over the property, and is linked to your SIRET.

Without a SIRET, the SIE cannot attach your activity to a CFE file. In practice, you may never receive a CFE notice, but that does not extinguish the liability. A regularisation can generate arrears for prior years.

For a detailed analysis of CFE in an LMNP context, see our article CFE and LMNP.

In LMNP files we take over mid-activity, the most frequent anomalies are not deliberate omissions but procedural misunderstandings. Many landlords believed they had declared their activity because they had ticked the BIC box on their personal income tax return. That does not substitute for the start-of-activity declaration and SIRET registration.

Another recurring issue: the start-of-activity date entered does not match the actual first rental date. It may reflect the purchase date, or an arbitrary date. Even a few weeks' discrepancy can create friction in a tax audit, and matters more since the LF 2025 reform (loi n° 2025-127 du 14 février 2025, article 84, amending article 150 VB of the CGI): depreciation claimed under the réel regime now reduces the acquisition price used for the private capital gains calculation on disposal, under conditions to be verified for each file. An inconsistent start date complicates that calculation. For more on that reform, see our article LMNP 2026 reform.

• Start-of-activity date identified and supported by documents (lease, inventory, first rental receipt)
• Declaration filed on formalites.entreprises.gouv.fr within 15 days
• SIRET received and stored in your file
• Tax regime (micro-BIC or réel) chosen and consistent with the declaration
• CFE: contact with the relevant SIE if in doubt about applicable exemptions
• DGFiP professional space created or linked to the SIRET if you are under the réel regime
• Depreciation schedule drafted if you opt for the réel regime, from the outset

Up to date as at 2026-05-26. This article is for information purposes only and does not replace personalised professional advice. For your specific situation, consult a registered expert-comptable.