Mortgage rates have risen again in 2026, with rates around 3.50% for 20 years and 3.60% for 25 years. For borrowers who took out a loan between 2022 and 2024 at significantly higher rates, the renegotiation window remains open. However, it could close if the upward trend continues in the fall.
Calculating the actual gain from such an operation requires going beyond a simple rate comparison and integrating variables that online simulators do not always show.
Actual cost of a renegotiation: the fees that the simulator does not detail
Most simulation tools display a gross gain, which is the difference between the interest of the old loan and that of the new one. This figure does not reflect the actual savings. Three categories of fees systematically reduce the net benefit.
Early repayment penalties (IRA) are capped by regulation at 3% of the remaining capital or six months of interest on the repaid capital, with the lower amount being retained. This legal cap applies to all contracts, but some banks negotiate its removal at the initial loan signing. Checking this clause in your original loan offer is the first step before any calculation.
In addition, there are the processing fees of the new bank (in the case of external buyout) and guarantee fees. If your initial loan was secured by a mortgage, the release generates notary fees. A guarantee like Crédit Logement may, on the other hand, lead to a partial refund of the mutual guarantee fund.
To find out how to calculate the gain from a mortgage loan renegotiation, you need to subtract these three items from the gross gain displayed by the simulator and compare the result to the total cost of the operation.
Rate differential and remaining capital: the profitability formula for a credit buyout
The rate differential is the most cited criterion, but it does not work alone. A differential of 0.80 points on a low remaining capital at the end of the loan will only produce marginal savings because the interest portion in each monthly payment has already significantly decreased.
The relevant calculation intersects three variables:
- The remaining capital at the time of renegotiation, which determines the base on which the new rate applies. The higher this capital, the more significant the impact.
- The remaining duration of the loan: a loan with more than half of the original duration left to repay generates significantly higher savings because the monthly payments still contain a high proportion of interest.
- The net rate differential, which is the difference between your current rate and the new proposed rate, after integrating the fees into the overall APR calculation of the operation.
In practice, the operation becomes profitable when the total gain exceeds all incurred fees, including IRA. This break-even point generally occurs in the first few years following the renegotiation. If you plan to sell the property before reaching this threshold, the credit buyout will cost you more than it brings in.
Borrower insurance: the overlooked savings lever in the overall calculation
Since the Lemoine law, any borrower can change their loan insurance at any time, without waiting for an anniversary date. This lever is often dissociated from the rate renegotiation, even though it can represent up to 20 to 30% of the total cost of the loan.
A young, non-smoking profile pays a considerable premium with a bank group contract compared to an external insurance delegation. The difference amounts to several thousand euros over the remaining duration of the loan. Combining a rate renegotiation with a change of insurance multiplies the net gain, sometimes more significantly than the mere rate reduction.
The trap is to accept the group insurance contract from the new bank during the buyout, under the pretext of simplifying the file. Field reports vary on this point: some banks unofficially condition the acceptance of the buyout on subscribing to their insurance. Regulations prohibit this practice, but commercial pressure exists.
Integrating insurance into the real calculation
To obtain the real cost of your loan after renegotiation, add the total interest of the new loan, the operation fees (IRA, processing, guarantee), and the total cost of insurance over the remaining duration. Compare this amount to the total cost of your current loan over the same period, insurance included. This overall comparison determines the true gain, not just the nominal rate differential.
HCSF debt threshold and wealth strategy after renegotiation
The framework set by the High Council for Financial Stability limits the debt ratio to 35% of income, including insurance, and the loan duration to 25 years (27 years in some cases involving work or a VEFA). This constraint transforms renegotiation into a wealth strategy tool.
Reducing your monthly payment through renegotiation can bring the debt ratio below the 35% threshold. A borrower blocked by this ceiling then regains borrowing capacity for a second project, whether it’s a rental investment or a secondary residence.
The trade-off between reducing monthly payments and shortening duration makes sense here. Lowering the monthly payment frees up immediate borrowing capacity. Shortening the duration decreases the total cost of the loan but does not change the monthly debt ratio, and may even increase it if the monthly payment remains the same.
The renegotiation window favorable to loans taken out between 2022 and 2024 remains open in 2026, but rates are rising. A serious calculation includes IRA, guarantee fees, insurance costs, and the remaining duration of the loan. A simple rate comparator is not enough to decide. The real gain is measured in net euros after deducting all fees, over the period during which you will actually keep the property.