Step 1: Put a meter on every room
A single meter for the whole building forces you to guess each room's share. A meter per room (or a sub-meter) turns the bill into arithmetic: units used × rate per unit. If sub-meters aren't possible yet, agree one fixed per-bed electricity charge in the agreement and say so up front.
Step 2: Take a reading whenever someone moves in or out
The month-end reading alone is not enough. If a tenant leaves on the 12th and a new one arrives on the 14th, the units used before and after belong to different groups of people. Note the reading, the date and who was in the room at every move-in and move-out.
Step 3: Divide the units among the people who were there
For each stretch between two readings, units used × rate gives that stretch's amount. Split it equally among the tenants who were in the room during that stretch. Someone who joined later pays only for the stretches they were part of.
Worked example (illustrative numbers): a 3-bed room, rate ₹8 per unit. Reading on the 1st: 1,200. Tenant C leaves and D arrives on the 16th, reading 1,260. Month-end reading: 1,320.
- 1st–16th: 60 units × ₹8 = ₹480, split between A, B and C = ₹160 each
- 16th–month-end: 60 units × ₹8 = ₹480, split between A, B and D = ₹160 each
- Result: A and B pay ₹320, C pays ₹160, D pays ₹160 — nobody pays for days they weren't there
Mistakes that cause arguments
- Changing the per-unit rate without telling tenants. Write the rate in the agreement or on the bill.
- Skipping the move-out reading and 'adjusting' later.
- Splitting the whole month's bill among whoever is there at month-end.
- Not showing the working. Tenants accept a bill they can check: opening reading, closing reading, units, rate, their share.
- Hiding a minimum or fixed charge inside the number.
Doing it without a calculator
PG Nexon follows exactly this method: you map a meter to each room, enter the reading when a tenant moves in or out, and the units are split among the tenants who were in the room, with each person's share added to their invoice. It uses one fixed rate per unit — tiered or slab tariffs aren't supported yet.