Hezia Core simulators
Debt-to-income ratio calculator
For a French mortgage, the reference set by the High Council for Financial Stability (HCSF) is the “debt-service ratio” (taux d'effort): your loan charges divided by your income. This calculator estimates it, with no account and nothing saved. Indicative only: it is never a lending decision.
Estimated debt-service ratio with the project
25.7%
Below the 35% reference threshold.
Your estimated debt-service ratio is 25.7%: €900.00 of monthly loan charges for €3,500.00 of retained income. A bank also looks at your remaining budget, your situation and the project. In simple mode, your current loans are assumed to run for the whole project term.
Theoretical extra monthly payment up to 35%
€1,225.00
Before the project: income × 35% − current charges. Never a loan offer.
Remaining margin after the project
€325.00
Up to the 35% threshold, first year.
Indicative remaining budget
€2,600.00
Retained income − monthly charges of the scenario. A budgeting indicator, not a single regulatory threshold.
Retained income
€3,500.00
Net before tax, rents discounted.
Indicative simulation based on the HCSF reference rule (maximum debt-service ratio of 35%, insurance included, net income before tax). Lenders have a regulated flexibility margin and review your whole situation: this result is neither a loan approval nor a refusal, and is not personalised advice.
No data from this simulation is stored: all calculations stay in your browser.
Understanding the debt-service ratio
Debt-service ratio or debt ratio?
“Debt ratio” is the everyday term. For French mortgages, the HCSF rule refers to the debt-service ratio (taux d'effort): annual loan charges (borrower insurance included) divided by annual income, × 100.
Which income?
Net income before tax, stable and recurring: salaries, pensions, regular professional income. One-off income is not retained by default.
What about rent?
Gross rent can be retained after a prudent discount (rental risk). It is added to income; the monthly payment stays whole in the charges — never “payment minus rent”.
Why the term matters
The debt-service ratio is assessed over the whole term of the new loan: if a current loan ends in a few years, the first, heaviest years are the reference.
Frequently asked questions
What is the debt-service ratio?
It is the share of your income spent on repaying your loans: loan charges (borrower insurance included) divided by your net income before tax, × 100. It is the indicator used by the HCSF for French mortgages.
Why 35%?
Since 1 January 2022, the HCSF decision of 29 September 2021 asks lenders not to exceed a 35% debt-service ratio (and a 25-year term) for most of their mortgages, to limit over-indebtedness.
Does rental income count?
Yes: gross rental income can be taken into account after a discount set by the lender to reflect rental risk. The HCSF does not set a single percentage; this calculator asks you for the discount to apply.
Is borrower insurance included?
Yes, when it is required to obtain the loan, borrower insurance is part of the loan charges included in the debt-service ratio.
Does exceeding 35% mean an automatic refusal?
No. Lenders have a regulated flexibility margin (up to 20% of their quarterly lending) and also look at the remaining budget, the situation and the project. Conversely, being under 35% guarantees no approval.
Official sources
- HCSF decision of 29 September 2021 on the conditions for granting mortgages (Légifrance, in French)
- HCSF — Measure relating to the granting of mortgages (in French)
- HCSF — Questions and answers on the mortgage decision (PDF, in French)
Rule checked on 12 October 2026.