Property tax reassessment: how does it really work?

Property tax reassessment: a key parameter in every buy or rent decision

When you compare whether it’s better to buy or rent, you usually look at purchase price, mortgage rate (around 3.6 % currently), notary fees, or the investment return you could get by staying a tenant. One element is often underestimated: property tax reassessment.

In the buy-or-rent.net / acheter-ou-louer.com simulator, this appears as the parameter taux_revalorisation_taxe_fonciere_annuelle (annual property tax increase rate). It is to property tax what the annual rent increase (linked to the IRL index in France) is to rent: a way to project your future cash flows realistically.

Understanding how property tax reassessment works, how it is linked to rental values (valeurs locatives) and how it affects your buy or rent decision is crucial if you want to compare homeownership to financial investments (ETFs, savings accounts, life insurance) in a data-driven way.

1. How is property tax calculated today?

Before talking about property tax reassessment, you need the basic formula. In France, the annual property tax on built property is roughly:

• Cadastral rental value of the dwelling (theoretical annual rent)
• – a standard allowance (usually 50 %)
• = net taxable base
• × tax rates voted by the municipality, inter-municipal body, department
• = annual property tax

Simple example:

• Cadastral rental value: €6,000 per year
• Allowance 50 % → base: €3,000
• Total local tax rate: 35 %
• Property tax = 3,000 × 0.35 = €1,050 in year 1

Two mechanisms then push this tax up over time:

• the national revaluation of rental values (automatic indexation, tied to inflation)
• local political decisions: higher or lower tax rates voted by the city, inter-municipality, department

Combined, they explain why property tax often grows faster than general inflation. This is exactly what the simulator’s taux_revalorisation_taxe_fonciere_annuelle tries to capture.

2. What is the revaluation of rental values (valeurs locatives)?

Once a year, the central government increases the rental values used as the basis for property tax. The adjustment is mostly indexed to inflation. In practice, the cadastral rental value of every property is multiplied by a factor.

Recent orders of magnitude (rounded):

• 2022: about +3.4 %
• 2023: about +7.1 % (exceptionally high)
• 2024: about +3.9 %

If your municipality keeps its tax rates unchanged, your property tax bill will broadly follow these percentages. The simulator parameter taux_revalorisation_taxe_fonciere_annuelle is precisely this: an assumed average annual increase you choose to project into the future.

10-year reassessment example

Assumptions:

• Initial property tax: €1,000
• Average annual reassessment rate: 3 %
• Local tax rates remain stable

Approximate evolution:

• Year 1: €1,000
• Year 5: 1,000 × (1.03)⁴ ≈ €1,125
• Year 10: 1,000 × (1.03)⁹ ≈ €1,305

In 10 years, your property tax bill is up by more than 30 %, even though local rates did not change. Over a 20–25 year mortgage horizon, the cumulative effect becomes material in any buy or rent analysis.

3. Property tax reassessment vs. inflation: which one wins?

From a wealth-building perspective, you should compare:

• Annual inflation (erosion of purchasing power)
• Annual property tax reassessment (taux_revalorisation_taxe_fonciere_annuelle)

If inflation runs at 2 % but property tax grows at 4 %, your tax burden is rising faster than your average purchasing power. This gap must be considered in a buy or rent comparison, alongside:

• the mortgage rate (e.g., 3.6 % fixed for 20–25 years)
• the borrower insurance rate (about 0.25–0.45 % of the insured balance)
• the investment rate you could get if you rent and invest your capital (3–5 % for diversified ETFs is a common assumption)

Once your mortgage is paid off, property tax doesn’t disappear. It often becomes one of the main recurring ownership costs, especially if reassessment outpaces inflation.

4. Concrete impact on a home purchase: two numerical scenarios

Scenario 1: moderate property tax, moderate reassessment

Assumptions:

• Purchase price: €300,000 (existing property)
• Notary fees: 8 % ≈ €24,000
• Agency fees: 4 %, already included in the price
• Mortgage: €300,000 over 25 years at 3.6 % + 0.30 % insurance
• Property tax year 1: €900
• taux_revalorisation_taxe_fonciere_annuelle: 2.5 %

Property tax evolution:

• Year 1: €900
• Year 10: 900 × (1.025)⁹ ≈ €1,140
• Year 25: 900 × (1.025)²⁴ ≈ €1,700

Approximate total paid over 25 years:

Using the future value of a growing annuity: total ≈ 900 × ((1.025)²⁵ – 1) / 0.025 ≈ 900 × 34.8 ≈ €31,320.

So you pay more than €30,000 in property tax alone over your mortgage term, in addition to:

• interest (over €150,000 for €300,000 at 3.6 % over 25 years, order of magnitude)
• borrower insurance premiums
• renovation costs (montant travaux, especially if you improve the energy rating)
• home insurance and maintenance

In a buy or rent comparison, this tax bill must be weighed against:

• the rent + annual rent increase (IRL-linked) on the tenant side
• the investment rate of the capital you keep if you don’t buy and don’t pay property tax

Scenario 2: high property tax, strong reassessment

Assumptions:

• Purchase price: €350,000
• Property tax year 1: €2,200 (tax-heavy city)
• taux_revalorisation_taxe_fonciere_annuelle: 4 % (combined national + local)

20-year evolution:

• Year 1: €2,200
• Year 10: 2,200 × (1.04)⁹ ≈ €3,146
• Year 20: 2,200 × (1.04)¹⁹ ≈ €4,819

Total over 20 years:

≈ 2,200 × ((1.04)²⁰ – 1) / 0.04 ≈ 2,200 × 29.8 ≈ €65,560.

More than €65,000 in property tax over 20 years is equivalent to:

• a sizeable down payment that could have been invested at a decent investment rate
• or several years of rent in some mid-sized cities

The buy-or-rent.net / acheter-ou-louer.com simulator lets you plug in different values for taux_revalorisation_taxe_fonciere_annuelle (e.g., 2 %, 3 %, 4 %) and instantly see how it changes the outcome of your buy or rent calculation.

5. Property tax reassessment: why your city matters

Property tax levels already vary hugely between cities (from €450–600 a year for a small flat in a low-tax town to €4,000–5,000+ for a house in a major metro). But reassessment dynamics also differ because local authorities vote their own rates.

Case 1: fiscally stable city

A municipality that hasn’t changed its tax rates for years:

• you mainly face national rental value revaluation (roughly inflation-linked)
• in the simulator, you may set taux_revalorisation_taxe_fonciere_annuelle close to expected inflation (e.g., 2–3 %)

Case 2: budget-stressed city

A municipality that frequently raises tax rates:

• on top of national revaluation, elected officials vote extra increases (e.g., +5 % one year)
• the effective average annual reassessment can exceed 4–5 % over time
• in your buy or rent scenario, you should test a “high” property tax reassessment rate

Numerical illustration:

• Year 1 property tax: €1,500
• Average national revaluation: 3 %
• Average local rate hikes: 1 %

Effective reassessment ≈ 4 % per year. Over 25 years, the cumulative bill can easily exceed €60,000.

6. Property tax, energy rating (DPE) and renovation costs

Property tax is based on rental values, themselves linked to criteria such as size, location, comfort level, and amenities. Current public policies around energy performance (DPE) may, in the medium term, influence how these values are set.

This connects directly with another simulator parameter: renovation cost (montant travaux). If you invest, say, €30,000 in insulation and heating upgrades to improve the energy rating:

• you lower your energy bills
• you likely increase your resale value
• but in the long run you may also make the property “better” in the cadastral grid, which can impact rental values

To compare buy or rent properly, you therefore need to integrate:

• property tax and its reassessment rate
• renovation costs (upfront or spread over time)
• the savings you get from lower energy consumption and from avoiding major works as a tenant

7. How to choose the taux_revalorisation_taxe_fonciere_annuelle in the simulator

In buy-or-rent.net / acheter-ou-louer.com, taux_revalorisation_taxe_fonciere_annuelle is an average annual percentage. Some non-binding benchmarks for your tests:

• Low scenario: 1.5–2 % per year (stable city, moderate inflation)
• Central scenario: 2.5–3 % (close to long-term inflation plus some local pressure)
• High scenario: 3.5–5 % (tax-hungry city, high inflation periods)

For a robust buy or rent analysis, it makes sense to:

• run at least two or three simulations: low, central, and high property tax reassessment
• look at how cumulative property tax compares with total rent paid in the “rent” scenario

The simulator also lets you adjust other critical parameters:

• Loan rate (taux du prêt) — default around 3.6 %, but you can input your bank offer
• Notary fees — 7–8 % in existing properties, 2–3 % in new build
• Investment rate (taux de placement) — expected return on the capital you keep if you rent
• Annual inflation — to evaluate the real (inflation-adjusted) cost of each scenario

8. Buy or rent: the specific role of property tax in the comparison

On the owner side, property tax is a charge that is:

• unavoidable (barring temporary exemptions)
• structurally increasing (via annual reassessment)
• independent from your mortgage (it persists after the loan is paid off)

On the tenant side, you don’t pay property tax, but you:

• face an annual rent increase (IRL-linked in France)
• don’t benefit from capital gains on the property, but can invest your savings at your chosen investment rate

In a 20–25 year buy or rent simulation:

• a moderate property tax reassessment may be offset by property appreciation and the fact that you stop paying rent once the loan is repaid
• a high property tax starting point, combined with strong reassessment, can tilt the balance toward renting, especially if your investment returns are attractive

There is no one-size-fits-all conclusion. The right choice between buy or rent depends heavily on:

• your city’s current property tax level
• its political and fiscal trajectory (past and likely future rate decisions)
• your time horizon (5, 10, 20+ years)
• your investment profile and the returns you can reasonably expect

9. Uncertainty and why scenario testing is essential

Local taxation is political by nature. Nobody can reliably predict over 20–25 years:

• how rental values will be recalculated in future reforms
• how your municipality will adjust its tax rates
• what inflation will look like in the long run

That’s why the simulator’s taux_revalorisation_taxe_fonciere_annuelle is not a forecast but a scenario tool. A pragmatic approach is to run:

• an “optimistic” scenario, e.g., 2 % per year
• a “central” scenario, e.g., 3 % per year
• a “stress” scenario, e.g., 4.5 % per year

And for each, compare the total cost of buying versus renting, taking into account:

• mortgage payments (loan rate, borrower insurance)
• upfront transaction costs (notary fees, agency fees)
• renovation costs (montant travaux), including energy upgrades
• rents paid or saved, including annual rent increase
• investment returns on any capital not tied up in the property

10. Final thoughts and disclaimer

Property tax reassessment is a key driver of the long-term cost of homeownership. Over 20 or 25 years, a difference of just one or two percentage points in taux_revalorisation_taxe_fonciere_annuelle can translate into tens of thousands of euros. Ignoring it can completely distort a buy or rent comparison.

However, there is no universal answer. Whether it is better to buy or rent depends on your personal situation, your city, your financial profile, and your expectations about interest rates, inflation, property prices, and property tax reassessment.

Important: all figures and examples here are for educational purposes only. They are not personalized financial advice. For decisions that significantly affect your wealth, you should consult a qualified professional.

To see the concrete impact of property tax reassessment on your own case, adjust the taux_revalorisation_taxe_fonciere_annuelle parameter and compare several buy or rent scenarios with realistic mortgage, rent, and investment assumptions:

Simulate your situation on buy-or-rent.net