MEES makes EPC ratings legally binding for landlords. Renting a domestic property below the threshold attracts fines up to £30,000 per breach + a published listing on the Trading Standards register.
Exemptions exist (Listed buildings where works would impair fabric; "all relevant improvements made" with the residual rating still sub-threshold; works that would devalue by ≥5%). Each exemption requires registration on the PRS Exemptions Register.
For prime-residential buyers the practical effect: pre-1900 stock + un-insulated leasehold flats are facing 5-15 year horizons before letting becomes restricted. Refurbishment costs to lift from E to C average £15-40k per UK flat.