Cross-border taxation of homeowners in the Pays de Gex: what you really need to know

Before going into the details of each real estate tax, it is important to remember a fundamental rule: if you are a tax resident in France and work in Switzerland, you are subject to the Franco-Swiss tax treaty of 9 September 1966. This treaty divides the taxing rights between the two countries to avoid double taxation — but it does not eliminate all of them, and above all, it does not make your Swiss income tax-neutral in France.

This is the point that many cross-border workers discover with surprise when they first declare themselves as landlords. France uses the so-called effective rate method: your Swiss income (taxed in Switzerland at source) is reintegrated into your French tax return, not to be taxed a second time, but to determine the tax rate applicable to your other French income — including your rents.

In concrete terms: if you receive CHF 90,000 in Swiss salary and €12,000 in rent in France, your rents will not be taxed at the marginal rate of a household that only earns €12,000. They will be taxed at the rate that would be applied by a household whose total income — including CHF — amounts to the global equivalent. The difference can be very significant depending on the situation.

For cross-border workers working in the canton of Geneva (which represents the vast majority of cross-border workers in the Pays de Gex), withholding tax in Switzerland applies in accordance with the specificities of the Franco-Geneva agreement. This creates a special situation: your salary is deducted in Switzerland, you declare in France, and the French administration includes this income in the calculation of the effective rate. The French declaration is mandatory, regardless of the Swiss tax method.

The good news about property tax is that it is not affected by your status as a cross-border worker. It is payable by any owner of a property in France, regardless of their professional situation or place of work.

In Ain — a department that includes most of the Pays de Gex — the municipal and intermunicipal rates vary according to the municipality. As an indication, for a 70 m² apartment in the border area, the property tax is generally between €800 and €1,500 per year depending on the municipality and the cadastral rental value of the property. Houses with land can exceed €2,000 per year.

Since the 2023 reform, the housing tax has been abolished for primary residences. If your property in the Pays de Gex is your main residence, you are no longer subject to it. On the other hand, if you own a second home in the region (a common phenomenon for certain cross-border profiles), the housing tax on second homes is maintained and remains due each year.

If you rent out your property, you should know that property tax is a deductible expense under the real property income tax regime. This is a deduction that is often underestimated — more on that in the next section.

If you decide to rent out your property — whether because you don't live there yet, because you've invested in a second property, or because you're going to Switzerland for a few months — you must declare this income in France in the category of property income.

Two regimes coexist:

The micro-property regime applies automatically if your annual gross rental income does not exceed €15,000. It grants you a flat-rate allowance of 30% on the rent received, without justification. Simple but often disadvantageous for cross-border owners.

The actual regime allows you to deduct actual expenses: property tax, loan interest, management fees, maintenance and repair work, non-occupant owner insurance, non-recoverable co-ownership fees. If your mortgage is large (which is common in the Pays de Gex with prices per m² between €4,400 and €5,500), the actual regime is almost always more advantageous.

Here is the concrete mechanism, which is often misunderstood. Let's take a numerical example:

A cross-border worker receives CHF 110,000 (approximately €118,000) in taxed salary in Switzerland, and €15,000 in net rental income in France after deduction of charges. In France, his return includes all of this income to determine the effective rate. The marginal rate applicable to rents is not that of a household with an income of €15,000 — it approaches the highest bracket. The €15,000 in rent can therefore be taxed at an effective rate much higher than what a cross-border worker who says to himself "I don't pay tax in France on my Swiss salary".

It is not double taxation — the treaty prohibits it. This is a legal amplification of the rate. The distinction is important, but the financial impact is real.

The Real Estate Wealth Tax (IFI) is often neglected by cross-border workers – wrongly for certain profiles.

The IFI is payable by any tax household whose net real estate assets exceed €1.3 million on 1 January of the tax year. This threshold is assessed after deduction of eligible debts (current mortgage, work to be financed).

Only debts allocated to taxable property are allowed as a deduction: the outstanding capital of your mortgage, work expenses financed by borrowing, taxes related to property (property tax). Personal non-real estate debts are not deductible.

An anti-abuse ceiling applies: if the gross value of the assets exceeds €5 million and the debts represent more than 60% of this value, the excess portion is only 50% deductible.

In the context of the Pays de Gex, where a 5-room house is commonly negotiated between €700,000 and €1,000,000, the IFI threshold is not out of reach for cross-border workers with high wealth – especially those who also own property in Switzerland, even modest ones on a Geneva scale.

When you sell your property, any capital gain is taxable in France according to the rules of common law. The Franco-Swiss treaty is clear: the capital gain on a property located in France belongs exclusively to French tax jurisdiction. It will not be taxed in Switzerland.

Your main residence is completely exempt from capital gains at the time of sale, provided that the property is actually your main residence on the day of the sale. This is the most common situation in the Pays de Gex.

The overall rate of the net taxable capital gain is 36.2% (19% income tax + 17.2% social security contributions). A progressive surcharge is added for net capital gains above €50,000, ranging from 2% to 6%.

The good news for cross-border workers: the mechanism of the effective rate does not apply to capital gains. This is taxed on a flat-rate basis, and your Swiss income does not increase the applicable rate.

If you have financed your purchase by releasing your LPP early, you should know that if you resell the property, you are in principle obliged to repay the amount withdrawn to your pension fund, unless the proceeds of the sale are reinvested in another main residence within 2 years. This is a constraint that is often forgotten at the time of resale.

As a cross-border homeowner, your French tax return is more complex than a standard return. Here are the forms you are likely to fill out.

Form 2042 (main declaration): the basis of everything. You declare your income from French sources. The tax credit linked to your Swiss income is also carried over to it.

Form 2047 (income received abroad): this is where you declare your Swiss salary. The French tax authorities provide in this form a help sheet for calculating the Swiss salary in euros, applying the official exchange rate (for 2025 income, the expected rate is around CHF 1 = €1.07, subject to confirmation by the administration).

Form 2044 (property income – real property regime): if you rent out your bare property and you have opted for the real regime, you detail your deductible rents and charges here. This form does not apply to furnished rentals.

Form 3916 (accounts abroad): any cross-border worker with a bank account in Switzerland — which is almost systematic — must declare it. Box 8UU of the main return allows you to indicate this. Pillar 3 contracts (Swiss life insurance) are declared in box 8TT.

The 2026 tax return campaign for 2025 income opened on April 9, 2026. The deadlines vary according to the department and the method of declaration (paper or online). In Ain, online declarations must generally be filed at the end of May or beginning of June — check the official dates on impots.gouv.fr.

This is a major novelty that directly affects cross-border homeowners: since 1 January 2026, the permanent rules on teleworking resulting from the amendment to the Franco-Swiss agreement have come into force. They replace the transitional agreement that allowed up to 40% of teleworking without tax consequences.

The new permanent regime introduces a threshold of 40% teleworking. Beyond this threshold, days worked from France are in principle taxable in France according to French rules — and not in Switzerland. For a cross-border worker who owns a property who receives rental income, this can change the basis on which the effective rate applies, and therefore the overall taxation of his rents.

If you are 50% telecommuting and you receive property income, the portion of your salary now taxed in France is added directly to your French taxable income — and no longer just as a basis for calculating the rate. The impact can be very different from what you were used to.

This change makes teleworking a tax parameter in its own right. If you are close to the 40% threshold, a specific analysis with an advisor specializing in Franco-Swiss taxation is recommended before changing your work organization.

In our experience of the Pays de Gex real estate market, several mistakes regularly come up among cross-border homeowners.

Neglecting the effect of the effective rate on rental income. This is the most common. A cross-border worker who rents out his property often thinks that his rents will be taxed low because he "doesn't pay tax in France". The reality is the opposite: his Swiss income brings his French tax rate to its maximum level.

Forgetting to declare Swiss bank accounts. Omission of Form 3916 is considered a tax offense, punishable by a fine per unreported account. All accounts held in Switzerland — current account, savings account, corporate account — are affected.

Poorly calibrating the rental regime (furnished vs. unfurnished). Opting for micro-land without having simulated the real regime, or choosing the LMNP without understanding that the deficit is not deductible from the overall income, are two mistakes that can cost several hundred euros per year.

Ignore the repayment of the 2nd pillar on resale. Many homeowners discover this obligation when signing at the notary's office, without having anticipated the corresponding financial flow.

Underestimating the value of the assets for the IFI. The market value of properties in the Pays de Gex has risen sharply in recent years. A property acquired for €400,000 ten years ago can be worth €700,000 today. If you own several properties, it is prudent to take stock of your IFI situation at the beginning of each year.