Settlements
Settlements are the calculation, billing, and invoicing of charges and payments for market and transmission-related activities between market participants and the ISO. The settlement cycle follows a specific timeline and process for publication of statements, invoices, payment advices, dispute submittals, and payments. Various charging rates, processes, schedules, and documents are listed below.
Payments and charges
Many specific charge type categories are used within settlements and invoice processes according to involvement in the Markets and RC West.
Payments calendar
- California ISO Payments Calendar 2026 12/08/2025, 1:48 PM
- California ISO Payments Calendar 2026 12/08/2025, 1:48 PM
- California ISO Draft Payments Calendar 2026 09/19/2025, 9:17 AM
- California ISO Draft Payments Calendar 2026 09/19/2025, 9:17 AM
- California ISO Payments Calendar 2025 03/31/2025, 2:15 PM
- California ISO Payments Calendar 2025 03/31/2025, 2:15 PM
- ISO RMR Payments Calendar Tool 03/20/2025, 11:04 AM
- California ISO Draft Payments Calendar 2025 09/20/2024, 10:11 AM
- California ISO Draft Payments Calendar 2025 09/20/2024, 10:11 AM
- California ISO Payments Calendar 2024 10/26/2023, 8:12 AM
- California ISO Payments Calendar 2024 10/26/2023, 8:12 AM
- RC West Annual Payments Calendar 10/29/2019, 8:50 AM
ISO charge codes
The ISO uses specific charge codes dependent on the type of charge.
- ISO Charge Code Matrix 02/14/2025, 10:36 AM
Market and administrative charge rates
Grid Management Charge (GMC) rates
GMC is assessed to wholesale market customers to recover California ISO costs. This section contains current and historical GMC codes and rates and a sub section detailing the GMC unbundling process from 1998-2000.
GMC rates are based on the budget and grid management charge process.
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| Grid Management Charge Rates 2004-2026 Effective Jan 01, 2026 | 01/16/2026, 12:01 PM | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Reporting ISO RTO Costs Effective Jan 01, 2026 Pursuant to FERC Order No. 668 | 01/06/2026, 9:57 AM | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Emissions and start-up costs
- Start-Up Cost Charge Analysis 03/04/2008, 7:49 AM
- Emissions Cost Invoice Template 07/09/2010, 4:51 PM
Transmission access charge (TAC) rates
The current transmission access charge is a two-part rate for each megawatt hour of internal load and exports and is used to recover transmission revenue requirements.
High voltage access charge rates
Wheeling access rates
Submittal requirements for participating transmission owner rate changes
- Presentation - Transmission Access Change Process Improvements - Oct 26, 2020 10/27/2020, 11:23 AM
- Video - Transmission Access Charge Process Improvements 05/18/2024, 7:43 PM
Settlement mitigation
Supporting information regarding settlement estimation methodology in the event of a system error.
- Estimation of Invoice Interest Deviation for Trade Date 06-30-2019 07/03/2019, 10:35 AM
- Estimation of RAAIM Settlement Beginning Trade Date May 1, 2017 06/18/2019, 8:06 AM
- Estimation of Fifteen-Minute Market Instructed Imbalance Energy EIM for Trade Date Mar 28, 2019 04/02/2019, 12:51 PM
- Estimation of MLC for Trade Date Mar 2, 2019 03/06/2019, 8:37 AM
- Estimation of RAAIM Settlement April 2017 Monthly Statement 07/17/2017, 3:35 PM
- Estimation of EIM Transfer Quantities v4.0 06/26/2017, 8:00 AM
- Estimation of Upward Ancillary Service Settlement 05/10/2017, 8:33 AM
- Estimation of Convergence Bidding CRR Adjustment Settlement 04/27/2017, 10:34 AM
- Estimation of Nodal and Resource Prices (Updated) 03/14/2017, 4:27 PM
- Estimation of Weekly Invoice Published Oct 26, 2016 10/26/2016, 10:48 AM
- Estimation of Weekly Invoice Published Oct 19, 2016 10/19/2016, 4:07 PM
- Estimation of Marginal Congestion Cost Breakdown Prices 10/05/2016, 3:43 PM
- Estimation of Weekly Invoice Published Jun 8, 2016 06/07/2016, 11:34 AM
- Estimation of May 2015 T+9M Billing 03/17/2016, 9:02 AM
- Estimation of Weekly Invoice Published Aug 5, 2015 08/05/2015, 6:10 PM
- Estimation of April 2015 T+55B Billing 07/27/2015, 3:54 PM
Amendment 60 - must offer waiver denial reports
- Total Start-Up Cost: July 17, 2004 - March 31, 2009 05/14/2012, 12:15 PM
- Total Minimum Load Cost July 17, 2004 - March 31, 2009 05/14/2012, 11:56 AM
Other processes
- Resources Electing PIRP Protective Measures 12/19/2014, 11:31 AM
Invoicing
Invoicing schedules for monthly and annual CRR auctions
- Invoicing Schedule for Jan-Dec 2026 Monthly and 2027 Annual CRR Auctions 11/20/2025, 9:14 AM
- Invoicing Schedule for Jan-Dec 2025 Monthly and 2026 Annual CRR Auctions (Revised) 10/29/2025, 4:38 PM
- Invoicing Schedule for Jan-Dec 2023 Monthly and 2024 Annual CRR Auctions (Revised) 11/06/2023, 8:17 AM
- Invoicing Schedule for Jan-Dec 2024 Monthly and 2025 Annual CRR Auctions 10/26/2023, 8:12 AM
- Invoicing Schedule for Jan-Dec 2022 Monthly and 2023 Annual CRR Auctions (Revised) 11/18/2022, 10:09 AM
- Invoicing Schedule for Jan-Dec 2021 Monthly and 2022 Annual CRR Auctions 11/20/2020, 2:53 PM
Reliability Must Run (RMR)
Settlement information for the annual agreements between the ISO and qualified generators.
- RMR Invoice Template Version 3 (Effective Jun 1, 2013) 06/12/2013, 11:04 AM
- Prior Period Examples and Guidelines 09/03/2002, 1:37 PM
Reliability Must Run (RMR) reporting
- RMR Section 5.5 Report Template 12/28/2010, 3:08 PM
- RMR Section 5.5 Report Procedures 12/28/2010, 3:07 PM
Disputes
Submit a settlement dispute form in CIDI*
*For scheduling coordinators only
- Settlement Dispute Form 09/12/2016, 11:45 AM
- Placeholder Dispute Form 04/08/2009, 9:33 AM
Recalculation settlements
View previous recalculation settlement documentsCredit policy
The credit policy is detailed in the ISO Tariff and the Business Practice Manual for Credit Management and Market Clearing. Consistent with the policy, market participants use the following forms to demonstrate that they meet the ISO minimum participation and financial security requirements and to request an unsecured credit limit.
- ISO Unsecured Credit Application 09/12/2025, 11:53 AM
- ISO Form Guaranty 09/12/2025, 11:53 AM
- ISO Form Letter of Credit 09/12/2025, 11:53 AM
- Officer Certification Form 09/12/2025, 11:53 AM
- California ISO Credit Management Frequently Asked Questions (FAQs) 08/03/2023, 10:06 AM
- Credit Management - Convergence Bidding Estimated Aggregate Liability Components and Data Flow 12/23/2020, 9:51 AM
- Credit Management - Congestion Revenue Rights Estimated Aggregate Liability Components and Data Flow 12/23/2020, 9:51 AM
The CIDI user guide is available on the application page.
If you are a scheduling coordinator and need access to settlement statements, invoices, ISO bill determinant files and SaMC configuration output files, visit the MRI-S application page for more information and the user guide.
- ISO Tariff 05/18/2024, 7:42 PM
- ISO Tariff, Section 11 - California ISO Settlements and Billing 01/16/2024, 9:51 AM
- Business Practice Manual for Credit Management and Market Clearing 05/18/2024, 7:41 PM
- Business Practice Manual for Settlements and Billing 05/18/2024, 7:41 PM