2025 NERC/WECC Metered Demand Calculations for Assessment Year 2027

The California ISO has posted North American Electric Reliability Corporation/Western Electricity Coordinating Council (NERC/WECC) information files to the Market Results Interface - Settlements (MRI-S) and the Secure File Transfer Protocol (SFTP) server on May 26, 2026. The files contain the NERC/WECC metered demand for assessment year 2027 for scheduling coordinator (SC) review, pursuant to ISO tariff section 11.20.4(a).

Information files can be retrieved in MRI-S by selecting NERC WECC INFO as the run type and setting the post date to May 26, 2026. The files are available on MRI-S and SFTP for 45 calendar days after publication. SCs are advised to download the files for validation purposes and future reference.

Item	Value	Unit
Total NERC/WECC Metered Demand for Calendar Year 2025	206,655,504.21	MWh
Estimated Preliminary NERC/WECC Charge Rate for Assessment Year 2027	0.068744605	$/MWh

2025 NERC/WECC metered demand is the summation of monthly NERC/WECC metered demand quantities published previously in the T+11M recalculation statements for Jan. 2025 through May 2025, and T+70B recalculation statements for June 2025 through Dec. 2025. Details regarding assessment of Charge Code 6490 NERC/WECC Charge are provided in the Business Practice Manual for Settlements & Billing configuration guide. It can be found in the Business Practice Manual Change Management webpage.

The NERC/WECC information files combined with this market notice shall serve as written notification of each SC's NERC/WECC metered demand for 2025.

Beginning May 26, 2026, each SC will have 60 calendar days to raise any disputes concerning the data calculation.

Contact information

Please contact ISO Customer Service at 916-608-7320 with any questions.