France rent calculations and renegotiation rules clarified

In France, landlords and tenants can adjust rent payments for partial‑month occupancy using two main methods. The "real‑month" method divides the monthly rent by the exact number of calendar days in the month, then multiplies by the days actually occupied, while the "30‑day" method assumes each month has 30 days for a simpler calculation. Both approaches should also apply to monthly service charges.

For rent renegotiations, the Climate and Resilience law restricts any increase for dwellings classified F or G on the energy performance index, effectively freezing rent and preventing landlords from offsetting renovation costs with higher rent. Tenants can use the landlord’s rising expenses—such as higher co‑ownership charges, property tax, and mandatory energy‑efficiency works—as a bargaining point, potentially offering a lower face rent in exchange for longer lease terms or shared renovation commitments. These strategies aim to balance the financial burden between parties while complying with French tenancy regulations.