How rates are set
What is rate design?
A cost-of-service study tells a utility how much each class should pay. Rate design is the art and discipline of deciding how they pay it — and it is where most of the real-world judgment happens.
The short answer: rate design is the step that converts each customer class's cost responsibility into the specific charges on a tariff — the customer charge, demand charge, and energy charge, plus any time-of-use pricing, seasonal rates, riders, or minimum bills. It balances cost alignment against practical goals like customer impact, stability, and simplicity.
Study first, design second
Rate design comes after the cost-of-service study, and keeping the two separate is what makes each rigorous. The study produces the "indicated" result — what the cost analysis says each class should pay. Rate design then decides how to get there in the real world, which is rarely a single overnight jump. Confusing the two is where many rate studies go wrong.
The building blocks of a rate
- Customer charge — a fixed monthly amount for connection, metering, and billing.
- Demand charge — based on peak kW, for larger customers.
- Energy charge — per kWh of usage.
- Time-of-use and seasonal rates — prices that vary by time of day or season to reflect when power costs more.
- Riders and adjustments — pass-throughs such as fuel or power-cost adjustments.
- Minimum bills and other tariff features.
Balancing competing goals
Good rate design weighs several objectives at once: aligning charges with cost, avoiding rate shock (gradualism), keeping rates stable and simple enough to understand, supporting conservation or policy goals, and staying fair across customers. These goals can pull in different directions, so rate design is as much about judgment and communication as it is about math — which is why utilities often model several scenarios and phase changes in over time.
Frequently asked questions
How is rate design different from a cost-of-service study?
A cost-of-service study decides how much of the revenue requirement each customer class should carry. Rate design decides how to collect that amount — through which customer, demand, and energy charges. The study is analytical; rate design is where analysis meets judgment about customer impact, simplicity, and policy.
Why don't utilities just charge everyone their exact cost?
Because moving instantly to strict cost-based rates could cause large, disruptive bill changes for some customers. Rate design balances cost alignment against other goals — gradualism (avoiding rate shock), stability, simplicity, conservation, and fairness — so it often phases changes in over time. This is why a study's 'indicated' rates are not always the rates that get implemented.
What are time-of-use and demand rates?
Time-of-use (TOU) rates charge different energy prices at different times of day to reflect when power is more expensive to supply, encouraging customers to shift usage off-peak. Demand rates charge based on a customer's peak kilowatt draw. Both are rate-design tools for tying charges more closely to the costs a customer actually causes.
Who has the final say on rate design?
It depends on the utility. A state commission approves rates for investor-owned utilities in a rate case; a member-elected board approves them for cooperatives; a city council or utility board approves them for municipals. Rate design has to satisfy both the cost analysis and the decision-makers who answer to customers.
Keep reading
How your electric bill is built
See these charges add up in an interactive breakdown.
What is a cost-of-service study?
The analysis that comes before rate design.
Rate360's Rate Design Studio lets utilities model scenarios and bill impacts before they commit to a change. See the methodology