A mortgage is a contract by which a bank provides a borrower with a sum intended to finance a purchase, construction, or renovation of a property. Before signing a loan offer, several mechanisms determine the total cost of the operation and the chances of obtaining a bank agreement. Knowing them in advance avoids calibration errors that can block a file or increase the final bill.
Debt ratio and HCSF standards: the regulatory framework for mortgages
The High Council for Financial Stability (HCSF) has been setting the rules that banks must follow when granting a mortgage for several years. Two criteria structure the analysis of any loan application.
The first is the maximum debt ratio of 35%, including borrower insurance. In practical terms, the sum of the loan payments must not exceed 35% of the borrower’s net income. The second is the maximum repayment period, capped at 25 years (27 years for a purchase in VEFA or with renovation work representing a significant part of the amount).
Discussions regularly resurface in public debate to relax these criteria. The French Banking Federation has thus advocated for a relaxation of HCSF rules. However, these requests have not changed the criteria applicable to borrowers. As long as the HCSF does not announce an official change, the 35% and 25-year caps remain the standard to be respected for any new loan application.
Understanding this framework allows one to calculate their borrowing capacity even before contacting a bank. One simply needs to subtract their fixed charges (other loans, pensions) from their net income, then check that the proposed monthly payment remains below the threshold. Several online simulators, such as the loan simulator on the Projet Immobilier website, allow for a quick estimate of this amount.
APR and total loan cost: the indicators to compare
The nominal rate displayed by a bank reflects only part of the actual cost of a loan. The annual percentage rate (APR) includes all mandatory fees: interest, borrower insurance, application fees, guarantee costs (mortgage, surety) and any brokerage fees.
It is the APR that should serve as the basis for comparison between two loan offers. A proposal displaying a low nominal rate but expensive borrower insurance can end up costing more than a competing offer with a slightly higher nominal rate.
Usury rate: the legal ceiling for the APR
The usury rate is the maximum rate at which a lender can grant a loan. Published quarterly by the Bank of France, it varies according to the duration of the loan. A file whose APR exceeds the usury rate will be automatically refused, even if the borrower presents a solid financial profile.
The rise in bond rates observed in 2026 has again weighed on mortgage lending conditions. When rates rise, the APR approaches the usury threshold, which can exclude certain profiles (older borrowers whose insurance costs more, modest incomes requiring a longer duration).
Borrower insurance: an often underestimated negotiation lever
Mortgage insurance covers the repayment of the remaining capital in the event of death, disability, or inability to work. While no law formally makes it mandatory, no bank grants a mortgage without this guarantee.
Its weight in the total cost of the loan is significant. Over a period of 20 years, insurance can represent a notable part of the APR. Two options exist:
- The group contract offered by the lending bank, often standardized with broad guarantees but a uniform price that does not take into account the individual profile of the borrower.
- The delegation of insurance, which involves subscribing to an external insurer. Since the Lemoine law (2022), any borrower can change their loan insurance at any time, without fees or penalties, provided that the new contract offers at least equivalent guarantees.
- Renegotiation during the loan term, relevant when the risk profile has changed (quitting smoking, changing jobs, improving health).
Comparing several borrower insurance quotes before signing the loan offer allows for a reduction in the APR without altering the terms of the loan itself.
PTZ and financing aids: what has changed recently
The zero-interest loan (PTZ) is a support mechanism for home ownership that allows financing part of the purchase without paying interest. Its eligibility conditions evolve regularly.
Since April 2025, the PTZ is again accessible for the purchase of new housing throughout the territory, including individual houses. Previously, new housing was limited to collective housing in tense areas. Existing properties remain subject to specific location and renovation conditions.
Income calculation for the PTZ: a recent rule to know
The method of calculating the income considered to verify eligibility for the PTZ has evolved. For offers issued since April 2025, the bank compares two amounts and retains the highest:
- The reference tax income N-2 of the future occupants of the housing.
- The total cost of the real estate operation divided by nine.
This mechanism can change the eligibility of a household whose tax income appears modest in relation to the project price. A borrower with declared low income but an expensive project could find themselves above the ceiling and lose the benefit of the PTZ.
The amount of the PTZ complements the main loan without substituting it. It reduces the amount to be borrowed at a standard rate, which decreases the monthly payments or shortens the repayment period.
The total cost of a mortgage depends on the interplay between rates, duration, insurance, and aids mobilized. Checking eligibility for the PTZ, comparing the APRs of several banks, and competing borrower insurances are three concrete actions that, combined, can represent substantial savings over the total duration of the loan contract.
