Increase in the residential surtax in 2026: Rent out a room for the long term to make your home profitable

Do you own one or more empty rooms in your primary residence, or do you own a second home that you rarely use? Beware: 2026 marks a major and particularly punitive fiscal turning point for under-occupied spaces. With the increase in local taxation, holding onto unused square footage is becoming a real financial drain. At Roomlala, we support thousands of hosts every day who are looking for ways to optimize their budgets. In this article, we will explain in detail how renting out a room, whether to a student or a young professional, can not only offset the 2026 property tax surcharge hike but also generate supplemental income that is entirely tax-free under certain conditions. Discover our complete guide to transforming this fiscal constraint into a real financial and personal opportunity.

Understanding the 2026 property tax surcharge surge and its impact on your budget

2026 does not look promising for owners of second homes or under-occupied housing. The calculation base for the property tax on second homes (THRS) is undergoing a flat increase of at least 3.9%. This mechanical rise in the tax base significantly increases local taxation, even before municipalities vote on their own rates. If you thought the abolition of property tax for primary residences would provide permanent relief, the reality is quite different for properties considered secondary or vacant.

Read also: Cedolare Secca 2026: The tax benefits of renting out a student room in Italy, New CIN regulations in Italy: Why hosts are turning to shared housing in 2026 and 2026 university start in Italy: Everything you need to know about the student contract (Contratto per Studenti)

The real blow comes from the massive expansion of the so-called "tax-burdened zone." Today, nearly 3,700 French municipalities are officially classified as tax-burdened. These municipalities, facing an acute housing crisis and high barriers to entry for long-term residents, now have the legal power to apply a steep surcharge to the property tax of second homes. This surcharge can fluctuate freely between 5% and 60%, depending on the city council's vote. The public authorities' goal is clear: to discourage under-occupation and force housing back onto the market for local inhabitants.

To illustrate this, let's take a concrete example. Imagine you own a nice apartment in Annecy or a family house on the Basque Coast, areas that are now ultra-burdened. If your property tax amounted to 1,000 euros, the 3.9% base increase first brings it to 1,039 euros. If the town hall decides to apply the maximum 60% surcharge, your final bill will climb to over 1,660 euros! Keeping a room empty or a home unoccupied for a large part of the year is therefore becoming a luxury that many can no longer afford. This is where an intelligent rental strategy is needed to neutralize this expense.

The strategic solution: transforming your empty space into a long-term rental

Faced with this unprecedented fiscal pressure, the most effective and responsible solution is to put these vacant spaces back on the long-term rental market. At Roomlala, we find that you don't need to rent out your entire home to make it profitable. Renting out a single furnished room in your home helps address the housing shortage while canceling or largely offsetting the property tax surcharge. Depending on your situation and that of your property, several lease formats are available to provide you with flexibility.

The landlord mobility lease: flexibility and profitability

The landlord mobility lease is a recent legal innovation that is increasingly appealing to hosts. It is a short-to-medium-term furnished rental contract, ranging from 1 to a maximum of 10 months, and is non-renewable. It is strictly reserved for tenants in temporary mobility situations: professional training, higher education, apprenticeship contracts, internships, or temporary work assignments. The huge advantage of this lease is its flexibility. It allows you to rent your room during periods when you do not need it, while regaining use of your property at a fixed date known in advance.

Take a very frequent use case at Roomlala: you own a large apartment in Bordeaux, a city subject to a heavy tax-burdened status. You can rent a room in your home to a young professional on a trial period or a seasonal worker for 6 months via a mobility lease. You thus generate rental income that largely covers your property tax and any potential surcharge, all while maintaining the freedom to reclaim your room to host family during the summer holidays. Additionally, this lease does not require a security deposit, which greatly facilitates the search for tenants, who are often covered by the Visale guarantee.

The student lease: an ever-growing rental demand

If you are looking for stability over an entire school year, the 9-month student lease is the ideal solution. The student housing crisis is a striking reality in all major French university cities. By opting for this type of rental, you provide an invaluable service to a young person in training while ensuring regular income from September to May or June. At the end of the 9 months, the lease ends automatically without you needing to provide notice, which guarantees you get your space back for the summer season.

For example, if you reside in Lyon or Rennes and your children have left the family nest, their old rooms represent untapped financial potential. By hosting a student, you not only bring life to your home but also create an often very enriching intergenerational bond. Financially, the rent collected over 9 months is more than enough to erase the impact of the 2026 property tax surcharge, turning a cost center into a true profit center.

Renting a room in your home and taxes: the guide to being tax-exempt in 2026

One of the best-kept secrets in real estate lies in Article 35 bis of the French General Tax Code (CGI). If you decide to rent a furnished room located inside your primary residence, you can benefit from a total income tax exemption on the rent collected. Yes, you read that right: 100% of the income generated can be tax-free. However, the tax authorities impose strict rules that must be followed to maintain this invaluable benefit in 2026.

The first condition sine qua non is that the rented room must be an integral part of your primary residence. This means it must not be completely independent. For example, an outbuilding at the end of the garden with its own entrance, its own meter, and no connection to your living space will not benefit from this tax exemption. The room must be a part of your house, even if the tenant has access to a shared bathroom or kitchen. Furthermore, the room must constitute the tenant's primary residence (in the case of a student) or their justified temporary residence (in the case of a mobility or seasonal worker lease).

The 2026 rent ceilings that must be strictly respected

To avoid abuse and guarantee affordable rents, the state sets annual rent ceilings that must not be exceeded to benefit from the "renting a room in your home" tax exemption. For 2026, these annual caps (excluding utilities) have been reassessed. They are set at 215 euros per square meter of living space in the Île-de-France region, and 159 euros per square meter in other French regions. It is crucial to calculate your rent precisely so as not to cross this red line.

Here is a concrete calculation example to help you. If you rent a 15 m2 room in Paris (Île-de-France), the annual rent excluding utilities must not exceed 3,225 euros (15 m2 x 215 euros), which is a maximum monthly rent of approximately 268 euros excluding utilities. If this same 15 m2 room is in Toulouse (another region), the annual cap will be 2,385 euros (15 m2 x 159 euros), or about 198 euros per month excluding utilities. Major warning: if you set a rent that exceeds these 2026 legal caps by even one euro, the tax exemption is simply canceled. Your entire rental income will then become taxable, usually under the micro-BIC regime (with a 50% deduction) or the real regime. At Roomlala, we advise you to adjust your rent carefully to take advantage of this highly beneficial tax loophole.

Procedures, standards, and safety: what you need to know before you start

While renting a room in your primary residence is relatively simple administratively, transforming an entire second home or a portion of it into a long-term rental requires some precautions. In many cities located in tax-burdened zones, changing the use of a property (moving from a second home to tourist accommodation or specific long-term rental) may require a prior declaration at the town hall. It is essential to contact your municipality's urban planning department to ensure your project is in full compliance with the Local Urban Plan (PLU).

Furthermore, energy performance regulations have tightened significantly. To offer a property for long-term rental, even if it is just a homestay room, the accommodation must meet decency standards for energy. Your home's Energy Performance Certificate (DPE) must not classify it as an "energy sieve" (grade G, and soon F and E according to the government schedule). Ensure your home is well-insulated and properly heated before signing a lease, or you risk the contract being declared void or facing sanctions.

Finally, getting started with room rentals can raise legitimate concerns. This is precisely why Roomlala exists. We provide a secure platform for you to publish your listing, verify the profiles of your future tenants, and manage payments with complete peace of mind. We also provide lease templates compliant with 2026 legislation, whether for a student lease or a mobility lease. For example, Marie, a Roomlala host in Montpellier, was able to rent her son's room after he moved abroad in just a few clicks. Thanks to our secure messaging system, she selected a trusted young doctoral student, signed a digitized student lease, and now receives tax-free rent that allows her to calmly finance her home renovation work, far from the worries of the property tax surcharge.