IT Release Schedule

Details of proposed changes to IESO systems and reports being revised for the current release are available here. Each release includes a preliminary, target and final planposted according to the IT Release Schedule. A yellow box indicates that the plan is not published for this release.

Target Release Plan

Final Release Plan

Release ID

Release R53.0  R53.1 R54.0 R54.1 
Release Category Category 3
(incl.Cat 2)
Category 3
(incl.Cat 2) 
Category 3
(incl.Cat 2)
Category 2 
Real Time Production Build 5 Mar 2025 4 Jun 2025 10 Sep 2025 3 Dec 2025
1. Preliminary Release Plan
Prepared
20 Nov 2024 19 Feb 2025 28 May 2025 20 Aug 2025
2. Market Participant Feedback
Period Ends
4 Dec 2024 5 Mar 2025 11 Jun 2025 3 Sep 2025
3. Target Release Plan 18 Dec 2024 19 Mar 2025 25 Jun 2025 17 Sep 2025
4. Final Release Plan 15 Jan 2025 16 Apr 2025 23 Jul 2025 15 Oct 2025
5. Sandbox Implementation 23 Jan 2025 24 Apr 2025 31 Jul 2025 23 Oct 2025
6(a). Production Build
(Non Real Time)
26 Feb 2025 28 May 2025 3 Sep 2025 26 Nov 2025
6(b). Production Build
(Real Time)
5 Mar 2025 4 Jun 2025 10 Sep 2025 3 Dec 2025

Four times per year, the IESO schedules a Preliminary Release Plan detailing upcoming changes to IESO systems that have been assessed to have an impact on participants. Comments on IT changes in the plan can be sent to pending.changes@ieso.ca. Each release includes a preliminary, target and final plan, categorized as the following:

  • Category 3 releases (occurring twice a year) require market participants to make changes to their own technical interfaces with the IESO. Normally, significant system changes are the subject of stakeholder consultation well in advance of this release process.
  • Category 2 releases (occurring four times a year) require market participants to make a change in procedure or to update documentation, but not to modify any IT systems.
  • Category 1 releases do not have any impact on market participants and are managed through the IESO's internal release process. Market participants are notified only of any applicable outages, via the Planned IT Outages webpage.

Updates to the Preliminary Plan are added to the Target Release Plan, which is also open for comment by participants. New items are added to the Target Release Plan if required, and are posted through the IT Release Schedule.

The Final Release Plan is published one week in advance of the Sandbox implementation date, when changes are made available in the Sandbox environment for testing and training. Participants can contact IESO Customer Relations for more information if Sandbox access is required.

After the testing period is complete, the IESO will release the changes in Production, as shown on the IT Release Schedule. Accompanying documentation for the changes is available on Pending Changes – Documents as part of the baseline process.