The 4CP successor
What Senate Bill 6 means for 4CP
Texas is rewriting how transmission costs get allocated. Senate Bill 6 ordered the PUCT to re-examine 4CP and adopt a final rule by December 31, 2026. The staff draft points at more coincident peaks measured over longer intervals, the 12CP direction. Everything you built around June through September afternoons is about to meet January mornings.
Rule tracker
PUCT Project 58484- ✓ Jun 21, 2025Senate Bill 6 signed. The PUCT must evaluate 4CP and amend its rules by the end of 2026. Bill history
- ✓ Aug 1, 2025PUCT opens Project 58484, Evaluation of Transmission Cost Recovery, the docket where the 4CP decision happens. Docket filings
- ✓ Fall 2025Workshop and two rounds of public comments. Familiar lines: large industrials defend 4CP, utilities and consumer groups push broader allocation.
- ✓ Mar 16, 2026Staff draft report recommends more coincident peaks than four, measured over longer intervals, plus tighter cost rules for large loads.
- ✓ Apr 13, 2026Comments on the draft report close. Final report and a proposed rule are the next docket milestones.
- Dec 31, 2026Statutory deadline for the final rule. WattMarkets ships the final-rule program config the week it lands.
What did Senate Bill 6 change?
SB6, signed June 21, 2025, ordered the Public Utility Commission of Texas to evaluate whether 4CP (the four summer coincident peaks that allocate wholesale transmission costs) still assigns those costs appropriately, and to amend its rules by December 31, 2026. The same bill tightened interconnection and curtailment rules for very large loads like data centers.
What is ERCOT 12CP?
12CP is a transmission cost allocation methodology that uses the highest system-demand interval of every month, twelve coincident peaks a year, instead of ERCOT's current four summer peaks. Your transmission charges would follow your average share of system load across all twelve intervals.
Is 12CP final?
No. The PUCT staff draft report of March 16, 2026 recommends moving from four coincident peaks to a methodology using more of them, measured over longer intervals than today's 15 minutes. A 12CP design measured in 30-minute intervals is the shape most parties are debating. The final report and the rule itself are still ahead, with a statutory deadline of December 31, 2026.
Why change 4CP at all?
Three reasons keep coming up in the docket. 4CP ignores winter peaks entirely, even though Texas scarcity events increasingly happen in cold snaps. A single 15-minute interval is a narrow target. And sophisticated loads have learned to duck the four intervals, cutting their transmission bills without cutting the system costs they cause.
How would 12CP change peak-chasing?
Under 4CP, response concentrates on hot summer afternoons. Under 12CP, every month has a peak that matters, including winter mornings. Curtailment strategies, battery schedules, and alert calendars all need to spread across the year, at roughly one-third the per-interval stakes.
When should I start planning?
Before the rule is final. The first year under a new methodology rewards whoever modeled it earliest, and the data to estimate your exposure under a 12CP allocation already exists in your interval meter history. WattMarkets ships a 12CP preview program so you can watch both scoreboards at once.
See your 12CP exposure before the rules land
The ERCOT 12CP · 2027 (draft preview) program runs inside WattMarkets today. Same instrument, twelve scoreboards. The Impact Estimator (enter a load profile, see the charge shift under the draft methodology) ships when the draft rule text is published.
Follow the transition
One email when the rulemaking moves, and one when 12CP goes live.