This week, a discreet signal from the bond markets. The French ten-year OAT, the benchmark for bank refinancing, crossed four per cent in July, while the mortgage rates displayed at branch counters still hold around 3.44% over twenty years. The gap is not trivial.

For anyone negotiating a Paris apartment this summer, for anyone waiting on a mortgage agreement in principle or finalising a preliminary contract, the question is not whether to give in to urgency. It is to understand why banks are lending today at a level their own refinancing cost makes uncomfortable, and how long that situation can last.

We are not calling a mechanical shift for the autumn. We are describing a technical mismatch that most buyers have not spotted, and which the banking calendar, historically, does not tolerate for long.

Mortgages: the gap that will not last

3.44% over twenty years. The rate on display in August 2026 is holding firm, even as the French OAT, the benchmark for bank refinancing, breaks through the four per cent mark. An untenable gap, which raises the question of the financing window still open to Paris buyers.

The rates observed this summer tell a strange story of stability. According to Pretto, mortgage rates in August 2026 stand at 3.33% over fifteen years, 3.44% over twenty and 3.52% over twenty-five, across all borrower profiles. The average rate across all durations, tracked by Crédit Logement-CSA, moves from 3.22% in the first quarter to 3.24% in the second: a barely perceptible shift. In the Île-de-France region, it reads 3.39%, the least competitive region in the country.

The paradox lies in how these rates are built. To construct their pricing grids, banks watch less the European Central Bank than the ten-year OAT, the rate at which the French State borrows on the markets. That rate has moved from roughly 3.6% at the start of the summer to more than 4% in July, pushed up by inflationary pressure on energy and a wider risk premium around France's budget trajectory. Over one year, the increase exceeds 0.70 percentage points, in a context where public debt represents 117% of GDP.

The ECB's decision to hold its key rates on 23 July, following the 0.25 point hike of 11 June, was anticipated by the markets and caused no shock to mortgage grids. Frankfurt's decision is a signal, not a driver. The driver is the OAT. And the OAT is now pulling in the opposite direction from the rates on offer.

When the OAT durably exceeds client rates, banks lend at a loss on their refinancing margin. The phenomenon is not new, but historically it lasts only a few weeks. Meilleurtaux puts it without ambiguity: as long as the level remains temporary, the impact stays limited; if it settles above 4%, a rise in mortgage rates becomes a likely scenario as early as September-October. Pierre Chapon, chief executive of Pretto, points out that banks adjust their pricing with a lag, never in real time.

The Paris context makes the calendar concrete. In the first quarter of 2026, 29,130 sales of existing homes were recorded in the Île-de-France, down 3% year on year, while the average price of existing apartments has stabilised at 9,600 €/m² in the capital. The Notaires du Grand Paris speak of a fragile recovery, in which the slightest shock could break the dynamic. The ECB, for its part, notes a tightening of lending criteria and a decline in credit demand in the second quarter. Buyers hold real negotiating power on price, but on files where the banking arrangement leaves no room for delay.

What our hunters observe on the ground confirms this reading. Files with a mortgage agreement in principle issued in July or August still benefit from the summer rates: banks do not retroactively lower them, but neither do they extend those conditions beyond their validity. A file signed at the preliminary contract in July, with the mortgage offer issued before the autumn, locks in a rate that the same lenders may no longer be offering six weeks later. The usury rate, set at 5.29% on loans of twenty years and more, will only be revised on 1 October: it leaves headroom, but not indefinitely.

One concrete lever remains, often overlooked. Between the catalogue rate and the rate actually negotiated, the gap can reach sixty basis points depending on the region. Comparing several banks, this summer, is not an excessive precaution: it is the only way to make use of the window before it closes.

Negotiate the rate, not only the price

The rate on the bank's catalogue is never the final rate. Between the display and the negotiated grid, the gap can reach sixty basis points. On a loan of several hundred thousand euros over twenty years, that represents tens of thousands of euros in interest saved. Playing three lenders against each other remains, in August 2026, the most profitable lever.

In the meantime, if a project is taking shape, we remain at your disposal for an initial conversation. We assess your brief against the market and deliver an unvarnished reading.