Ratio utility billing system (RUBS): how to run one by hand

A ratio utility billing system (RUBS) splits one bill a utility sends for a whole building across the units in it, using a ratio such as occupants or square feet instead of a meter per unit. You run one by choosing the ratio for each utility at each property, computing each unit's share of every bill, and charging it to the tenant's ledger. The calculator above does the split for one bill on your own rent roll, and this guide covers the choices behind it.

What does a ratio utility billing system do?

It turns a single property-level bill into a charge per unit. The utility bills the owner or manager for the building's total, there is no meter per unit to read, and the lease says tenants pay a share. The system supplies the share: each unit's weight (people, area or one) over the sum of weights, times the bill.

That is all the arithmetic there is. The work is in the inputs: who lives where, for how many days, what the lease says about each utility, and which bills are the shared ones. Most errors in a hand-run system come from stale occupant counts and a bill filed against the wrong property, not from the division.

Which ratio should a RUBS use?

There are three common ratios, and the lease decides which applies:

• Occupants. A unit with 3 people weighs three times a unit with 1. It tracks water and sewer use better than area does, but only if the occupant count is current and the lease permits it.
• Square feet. Area is fixed and easy to verify, which makes it a common choice for gas or heat shared across a building.
• Equal share. Every unit weighs 1. It suits a flat charge, such as trash collection billed per building.

You can use a different ratio for each utility and each property. Utility Billback keeps that choice per property and utility type, so the water bill at one building can split by occupants while its trash splits equally. Local rules on what you may charge, and how you must disclose the method, differ by state and city: this is not legal advice, so check them and your lease.

How do you work out a RUBS split, step by step?

1. Gather the bill's facts. The utility, the amount due for the current charges and the service period's first and last day.
2. List the sharing units. Only units whose lease says the tenant pays a share of this utility. Units where the owner pays, or where the tenant holds their own account, are out.
3. Pick the weight. Occupants, square feet or 1, from the property's rule.
4. Multiply the weight by days. A lease's weight is its basis times its days within the service period.
5. Divide. Share = the lease's weight over the total weight, times the bill, in whole cents, with the leftover cents given to the largest remainders so the total is exact.
6. Decide on vacant days and apply any cap per unit you set.
7. Record the charge with the bill it came from, so any tenant question can be answered from the bill.

What does a worked example look like?

A water bill of $480.00 covers 30 days for a four-unit building that splits by occupants. Units A, B, C and D have 1, 2, 2 and 3 occupants for the whole period, so the total weight is 8 people, and each person carries $60.00. The shares are $60.00, $120.00, $120.00 and $180.00, which add up to $480.00.

Now unit D's tenant moves out after day 15 and the unit is empty for the rest. D's weight drops to 3 people times 15 days. The others carry their basis times 30 days. In person-days that is 30, 60, 60 and 45, with 45 person-days left vacant, 240 in all. At $2.00 a person-day, D's tenant pays $90.00 and the owner keeps the $90.00 of vacant days, if your rule says so. The RUBS billing guide covers moves in more depth.

Where does a RUBS go wrong?

• Occupant counts that are out of date. A split by occupants is only as good as the count on the rent roll.
• A bill matched to the wrong property. The service address on a bill is the safest key. Normalizing street suffixes and unit markers before matching avoids missed matches.
• Move-ins and move-outs ignored. Charging the current tenant the whole month penalizes them for the previous tenant's days.
• Bills still in your name. Some utility accounts that the lease puts on the tenant never get transferred, so the company pays and nobody bills. A ratio system never sees those bills unless you look for them. One property manager's complaint about this was that "we end up paying a bill that we should be adding to the tenant ledger." See utility billback for how to find them.
• Rules you are not allowed to apply. Some places limit RUBS charges or require specific disclosures. The system will not know.

When is a RUBS not the right tool?

When each unit has its own meter, you bill what the meter says, and the ratio is unnecessary. Where there are submeters, the choice is about billing software for meter data, which is a different problem from the one on this page. A RUBS also does not read your bills for you: someone still opens each PDF and keys in the amount and period.

How does Utility Billback run a RUBS?

You upload the month's bill PDFs and your rent roll. Each bill is read for provider, service address, account name, service period and amount, and you check it beside the PDF before anything is used. Shared bills are split by the property's rule in whole cents, prorated by lease days, with vacant days kept by the owner or shared as you set. You then download a tenant charge CSV with the column names you chose once. It does not post charges to AppFolio or Buildium: you import the CSV. A scanned bill with no text goes to manual entry.

To try the arithmetic first, the RUBS calculator splits one bill free, and the sample month shows four bills of a 12-unit building worked through.

Frequently asked questions

Is RUBS the same as submetering?

No. A RUBS divides a bill by a ratio, and submetering bills each unit for what its own meter recorded. See RUBS utility billing for how the options compare.

Can I use a different ratio for water and trash?

Yes. The ratio is chosen per utility, and many properties split water by occupants and trash equally. Make sure each lease supports the method you use.

Do I have to prorate for move-ins and move-outs?

Prorating by lease days is the fairest way to avoid charging a tenant for someone else's days, and it is how Utility Billback splits shared bills. Whether your lease requires it depends on the lease and local law.