Replacement of the Settlement System

The Replacement of the Settlement System (RSS) is a strategic project that will sustain and integrate IESO’s settlements services by addressing issues with the existing settlement solution, create transparency and efficiencies in the process to address settlement statement disagreements, and enable the implementation of the new settlement design requirements required to deliver settlements for the up-coming Market Renewal Program (MRP). Following purposeful engagement with stakeholders to finalize the detailed design, the project is now in the Implementation Phase.

An overview of the specific changes planned by the RSS project, can be found in the July 21, 2022 Stakeholder Engagement presentation on RSS or view the recording (minute 22 to 60).

Changes under RSS for Market Participants

RSS will implement a number of changes for Market Participants as listed below:

  • Enhancements to Online Settlement Form submissions
  • Enhancements to Notice of Disagreement System
  • Amendments to the Settlements Disagreement and Resettlements Process
  • NEW – Recalculated Settlement Statements (RCSS) will be introduced
  • Amended Settlement Charge Types and Equations

The IESO will be supporting these changes by publishing advice and training materials to aid the transition for Market Participants.

Project Schedule

Update: The RSS In-Service date has been delayed; the IESO will provide fair notice prior to a new implementation date in 2023. There will also be opportunities for training from the IESO in the new year, ahead of the implementation date.

February 2022

Finalization of Detailed Design documentation and engagement on Market Rules and Market Manual changes

July 2022

Release of Updated Settlement Calendars, Data File Format Specifications, and Charge Types and Equations

Release of Format Specifications for Transmission Tariffs and Capacity Auction Data Files

August 2022

Market Trials Participant Signup Period (August 8-22)

Market Manuals Revisions released (mid August)
Test Cases released for Market Trials (late August)
Training Guide for Tool Revisions available (late August)

September 2022

Structured Market Trials (September 6-30) for Online IESO - Forms and Notices of Disagreements 

October 2022

Market Participant Business Process preparations

TBD, 2023

IESO release of statement examples to RSS webpage

TBD, 2023

IESO Training for Settlements staff (regarding RSS changes)

TBD, 2023 October 31, 2022

Final Trade Date for use of existing Settlement System and Market Rules

TBD, 2023 November 1, 2022

RSS In-Service date (new formats will take effect for any Settlement Statements related to the TBD Nov 1 Trade Date and beyond)

RSS Market Rule revisions take effect

10th Business Day after RSS In-Service date

November 16, 2022

First PSS Statements issued in new RSS format (for TBD Nov 1 Trade Date)

20th Business Day after RSS In-Service date November 30, 2022

First FSS Statements issued in new RSS format (for TBD Nov 1 Trade Date)

How can Market Participants prepare for RSS Changes?

Eleven revised documents, including Settlement Payment calendars, Data File Format Specifications, and IESO Charge Types and Equations, have been posted to the IESO’s Pending Changes - Documents webpage. Market Participants are encouraged to have their Settlement staff, as well as any third party service providers, review these materials and consider:

  • Which changes/additions to Online Forms will impact their business processes
  • How to modify any existing automated tools, processes, and downstream systems to reflect some limited changes to the charge types and data file specifications
  • How to revise internal business processes to incorporate the new Notice of Disagreement (NoD) windows and limitation period
  • What will be the frequency of the new Recalculated Settlement Statement (RCSS) Statements

Additional Published Documents

The following market manuals are draft versions being posted here to support market participant readiness in preparation for the RSS project implementation in 2023. The IESO will officially implement these changes through the Baseline process (Timeline TBD), which will allow for market participant comments and feedback.

  • Market Manual 2: Market Administration, Part 2.1: Dispute Resolution
  • Market Manual 3: Metering, Part 3.9: Conformance Monitoring
  • Market Manual 5: Settlements, Part 5.7:  Settlement Process
  • Market Manual 5: Settlements, Part 5.8: Settlement Invoicing
  • Market Manual 5: Settlements, Part 5.10: Settlement Disagreements
  • Market Manual 5: Settlements, Part 5.5: Physical Market Programs (Coming soon)

September Market Trials

The RSS Market Trials were conducted from September 6 to September 30, and were open to all IESO-registered organizations, but targeted towards LDC and other participants who use online form submissions.  Volunteers came forward from 36 distinct Market Participant organizations to register for Market Trials, returning back a total of 52 Test Cases on the new system. 

The RSS Market Trials involved four weeks of structured testing where Market Participants tested the new and updated Online Settlement Forms, as well as changes to the Notice of Disagreements system. The IESO also provided a sample set of PSS, FSS, and RCSS statement files that Market Participants used to verify the updated format and newly introduced charge types (details are within the 11 online documents found in the links above). Market Participants were also encouraged to take this opportunity to test and revise their own internal business processes and downstream systems against these changes. RSS Test Cases, Sample Statement files, and draft User Guides were provided to participants as part of the Market Trials activities.

Market Trials are now concluded, and no further testing is anticipated by those volunteers, other than for their own internal systems.  Submitting both NODs and Online Forms worked reasonably well with only minor issues, while the sample Statements identified issues of more significance.  IESO is now addressing the testing results and defects noted, and implementing system corrections in advance of RSS Go-Live.  The initiative and hard work of the volunteers is greatly appreciated by the IESO, and serves the interests of the entire Ontario electricity market, towards having a well-functioning end solution.

For More Information

More information, additional documents and next steps will be updated to this page as the RSS Project progresses. Please contact if you have questions about the RSS Project.