Hi,
Normally it is the position where the landlord has a secondary metre installed and the landlord is billing the tenant for the electricity used.
In this situation the charges to the tenants for the gas and electricity they use are consideration for separate supplies of fuel and power. These supplies will be standard-rated unless the fuel supplied is of a de-minimis quantity, in which case the supply will be subject to the reduced rate.
So if you as the tenant are charging for the known usage of electricity of another tenant back to the landlord then the liability will also be 20% VAT unless it is of a deminimus quantity where it will be 5%.
Please see below:
Fuel and power (VAT Notice 701/19): 3. Qualifying use
Thank you.