Simulateur de Financement

Summary

A financing simulator that allows a Pro or an Acheteur to estimate monthly mortgage payments, total loan cost, and eligibility for fiscal incentive schemes (Pinel, PTZ, etc.) based on a property price, down payment, loan duration, and interest rate. The tool is intended to be embedded on Lot and Programme detail pages, giving users an instant projection without leaving the product. As of April 2026, this feature is not yet implemented.

State Diagram

stateDiagram-v2
    state "Saisie des paramètres" as InputForm
    state "Calcul en cours" as Calculating
    state "Résultats affichés" as ResultsDisplay

    [*] --> InputForm
    InputForm --> Calculating: user submits parameters
    Calculating --> ResultsDisplay: computation complete
    ResultsDisplay --> InputForm: user adjusts parameters
    ResultsDisplay --> [*]: user closes simulator

Steps

1. Parameter Entry (Actor: pro / acheteur)

The user fills in simulation inputs: property price (pre-filled from lot/programme), down payment amount or percentage, loan duration (years), and estimated interest rate. Optional: toggle fiscal scheme eligibility (Pinel, PTZ, BRS, etc.).

Triggers: User opens the simulator panel on a Lot or Programme page Outcome: Input parameters ready for computation

2. Computation (Actor: system)

Client-side or server-side calculation of monthly payment (standard annuity formula), total interest cost, and net effective yield for the selected fiscal schemes. No external API call is required for the base simulation.

Triggers: User submits the form or changes a parameter Outcome: Numeric results: monthly payment, total cost, scheme-adjusted net price

3. Results Display (Actor: pro / acheteur)

Results are shown inline — monthly payment prominently, with a breakdown of principal vs. interest, and a per-scheme comparison table if fiscal schemes were selected. A Pro can share or print the simulation summary.

Triggers: Computation complete Outcome: User sees projections and can iterate on parameters

Error States

• Invalid input (negative price, duration = 0, etc.) → validation message inline, no HTTP error

Related Processes

• fiche-express-lot — a financing simulation summary could eventually be embedded in the lot PDF fiche
• fiche-express-programme — same potential inclusion at programme level