Why RUBS is the wrong way to bill for EV charging
No. Do not put EV charging energy into a RUBS pool. Ratio utility billing splits one master bill among units by occupancy, square footage or bedroom count, and EV charging correlates with none of those. The result is that the household with no car subsidises the neighbour's commute, which is the exact grievance that turns a charging project into a standing agenda item. It is also legally exposed in several states, and in at least one common rule the energy used at common facilities is the owner's cost by regulation, not the residents'. Meter the chargers instead. The charger can do it.
Updated 2026-08-20
What RUBS actually is
A ratio utility billing system takes one master-metered utility bill and divides it among units by a formula rather than by measurement. The usual inputs are unit square footage, occupant count, bedroom count, or a blend of them.
Why EV load breaks the formula
Charging energy is concentrated in a small number of households and it is large. A resident who drives 1,000 miles a month draws roughly 330 kWh to do it, which is on the order of a third of an average apartment's entire monthly electricity use — and that resident might be one unit in eighty.
The one number that decides whether anyone complains
The complaint is not driven by the dollar amount. It is driven by the ratio between what a non-driver pays and what a driver pays for the same kilowatt-hour.
Where formula allocation is restricted or must be disclosed
This varies by state, and the rule usually lives with the state public utility commission rather than in landlord-tenant law, which is why property managers often miss it.
What to use instead, by property size
The right arrangement is the cheapest one that measures the actual kilowatt-hours a specific person took. Every option below does that; they differ in who does the collecting and how much overhead you carry.
The one case where a shared cost is defensible
There is a version of common-cost absorption that boards accept, and it is not RUBS.
What to do before the chargers go in
Decide the billing method before the conduit is set, because the billing method decides the wiring.
Can we add EV charging to our existing RUBS pool for water and trash?
You should not, and in some states you may not. Water and trash allocation rests on the argument that consumption scales with occupancy. Vehicle charging does not scale with occupancy at all — it scales with which specific households own an EV. Adding it to the pool imports a defensible method into an indefensible use, and it puts your whole RUBS arrangement in front of a resident who now has a reason to challenge it.
What if we only charge the residents who own an EV?
That is better, but it is still allocation rather than measurement, and it fails as soon as two EV owners drive very different distances. A resident who drives 400 miles a month and pays the same as one who drives 2,000 will notice. If you already know which units have EVs, you are one step away from metering them properly, and metering is what makes the charge collectible without argument.
Does putting the chargers on the house meter make this simpler?
It makes the install simpler and the billing harder. House-meter energy is what gets allocated, so charging load lands straight back in the pool you were trying to avoid. It can also change which rate schedule the whole property sits on, which is a bigger financial event than the charging itself. That trade-off is covered in the house meter versus separate meter article in this cluster.
Do submeters have to be certified for billing?
Where you sell electricity by the kilowatt-hour, weights-and-measures rules can apply to the measuring device. NIST Handbook 44 §3.40 covers electric vehicle fueling systems and became a permanent code effective January 1, 2023, and state weights-and-measures agencies adopt and enforce it on their own schedules. Ask your equipment vendor for its type-evaluation status and ask your state agency what it requires — the answers are not the same everywhere.
Is there a federal tax credit that offsets any of this?
No. The Section 30C credit terminated for property placed in service after June 30, 2026, and there is no federal replacement. Anything recoverable now is a state, utility or local program. Treat a federal credit line in any charging proposal you receive today as an error to be corrected before you sign.
- 16 Tex. Admin. Code §25.141 — Central System or Non-Submetered Master Metered Utilities (Public Utility Commission of Texas)
- Public Utility Commission of Texas — §25.141 rule text (PDF)
- National Consumer Law Center — An Introduction to Ratio Utility Billing Systems for Tenant Advocates
- CPUC Decision 11-07-029 — whether selling EV charging services makes a seller a public utility (California)
- NIST Handbook 44 §3.40 — Electric Vehicle Fueling Systems
- IRS — Alternative Fuel Vehicle Refueling Property Credit (§30C status)
Price the metered version
Port count, where the stalls sit relative to the service, and whether you are running submeters or networked units all move the number. Answer those and you get an installed-cost range for your property in the same session.