This scenario applies proposed changes to ERCOT transmission billing to Oncor Transmission Service: twelve monthly peaks (12CP), annual class-allocation updates, and a minimum billing demand.
Service overview
| Item | Coverage |
|---|---|
| Service | Texas · ERCOT · Oncor Transmission Service. |
| Policy basis | PUCT Project 58000 proposal published July 24, 2026. |
| Scenario timing | 12CP and minimum billing demand apply throughout the forecast. Annual class-allocation updates begin in 2030. |
| Supply and delivery | Wholesale supply, distribution, customer service, and metering follow the Oncor Transmission Service page. |
Charge breakdown
| Line item / what it pays for | Tariff Charge Type | How the Charge Is Assessed | Calculation basis |
|---|---|---|---|
| Wholesale electricity supply | Supply | Energy | Imported MWh multiplied by the ERCOT wholesale price. |
| Distribution service and included riders | Distribution | Capacity (demand-based) | Monthly peak imported MW multiplied by the combined distribution and rider rate. |
| Customer service | Distribution | Fixed | Monthly customer amount. |
| Standard metering | Distribution | Fixed | Monthly metering amount. |
| Transmission cost recovery (12CP and minimum demand) | Transmission | Fixed | Maximum of (contracted MW, prior-year maximum imported MW, customer 12CP MW) multiplied by annual rate in $/MW-year divided by 12. |
How charges are calculated
Monthly peaks and minimum demand
Customer 12CP demand is the average customer demand at the highest 30-minute ERCOT system demand in each of the twelve months. The forecast combines 12CP with a minimum billing demand:
Billed demand in MW is the highest of contracted demand, the previous year’s maximum imported demand, and the customer’s twelve-coincident-peak (12CP) demand.
Monthly transmission cost is calculated by multiplying billed MW by the annual rate in $/MW-year, then dividing by 12.
The forecast uses campus nameplate capacity for contracted demand unless a different contract quantity is provided. Prior-year maximum demand and customer 12CP demand are provided for each billing year.
These annual billing quantities set one fixed monthly charge. Changing the operating schedule does not change that charge.
Forecast methodology
| Charge | How its rate changes |
|---|---|
| Transmission costs | Uses the ERCOT transmission-cost forecast and the Oncor recovery calibration. |
| Class allocation | Held at the existing allocation before 2030. From the assumed update year, class billing demand is divided by estimated Oncor 12CP demand. The system measurement window is the twelve months ending in September of the preceding year. |
| Customer billing demand | Uses the largest of the three annual demand quantities in the formula above. |
| Other charges | Use the current-policy Oncor supply and delivery rate forecasts. |
Assumptions and limitations
| Assumption | Effect on results |
|---|---|
| Timing | Class-allocation updates use the prior October–September measurement window. |
| Missing history | Missing prior-year maximum demand and customer 12CP demand are treated as zero. Contracted demand then sets the bill unless another provided quantity is larger. |
Public tariffs and regulatory filings
| Source | Coverage |
|---|---|
| Project 58000 proposed rules | Proposed 12CP, measurement interval, annual allocation, and minimum-demand framework. |
| Oncor Retail Delivery Service tariff | Schedule 6.1.1.1.7: baseline delivery charges. |
Methodology version: October 2026. Results use real 2025 dollars.