Introduction to the IESO's Transmitter Selection Framework

Ontario’s electricity sector is undergoing a period of rapid transformation, driven by growing demand, economic development, electrification, and emerging technologies. To meet the projected increases in electricity needs over the next 25 years, the IESO is advancing efforts to support resource acquisition and the expansion of Ontario’s transmission system. These activities aim to help ensure that electricity remains reliable and affordable, when and where it is needed.

As part of this work, the IESO is developing the Transmitter Selection Framework (TSF) — a strategic initiative designed to introduce transparency, competition, and cost-effective investment for new transmission infrastructure. The TSF will establish a competitive process for selecting transmitters, aiming to deliver greater value to ratepayers, encourage innovation, and create opportunities for Indigenous participation.

The TSF was initiated following the release of the Powering Ontario’s Growth (POG) report in July 2023 and is further guided by Ontario’s Integrated Energy Plan (IEP). The TSF aligns with the government’s direction to expand the transmission system in a timely and co-ordinated manner, including through competitive procurement for specific new transmission projects.

Further updates will be shared through upcoming engagement sessions and posted on this web page. We encourage you to check back regularly and participate in future TSF engagement activities.

TSF Updates

A focused engagement session was held on June 25, 2025, to present the final Registry Rules along with design considerations for the commercial framework and the Indigenous Engagement and Participation Plan (IEPP).

A summary of all feedback received and the IESO’s responses can be found at the TSF Engagement link below.

The IESO will endeavor to schedule the next engagement session for September 2025, which will include proposed commercial terms and additional RFP design details.

For further information about upcoming engagement sessions, please visit the IESO’s Transmitter Selection Framework Engagement webpage.

Any general enquiries regarding the TSF can be sent to TSF@ieso.ca.

TSF Registry

Stakeholder and Community Engagement​

Learn more about the engagement plan, objectives, approach, timeline and considerations for engaging stakeholders and communities.

Subscribe for Updates

Visit the IESO's subscribe page to sign up for future TSF updates.

TSF Documents

TSF Registry

The IESO is launching the TSF Registry as the first step in implementing the TSF. It is intended to streamline the screening process by identifying and pre-assessing transmitters in advance of future procurement opportunities.

TSF Workspace

Log in to Workspace

Sign up for Workspace:

Email TSF@ieso.ca with subject line TSF Registry: Workspace Access with the following details: Company, Name, and Email address for primary and secondary (if required) users requesting access.

See Registry Rules for full details.

TSF Registry Documents

The final TSF Registry documents will be published when the TSF Registry officially launches.

Disclaimer

The Transmitter Selection Framework Registry (“TSF-R” or “The Registry”) and the statements and information contained therein, are based on the proposed design as of the date of posting and remain subject to amendment following the process set out in the TSF Registry Rules. Nothing in the TSF Registry Rules, or the posting thereof, obligates the IESO to continue or conduct the procurement process contemplated herein, or any other procurement process. Nothing in the posted TSF Registry Rules, RFP or contract (as applicable), nor shall it be construed to constitute, an agreement, guarantee, representation, or warranty, express or implied, on behalf of the IESO. The IESO provides no such agreement, guarantee, representation, or warranty and disclaims any and all liability associated therewith. In the event there is any conflict or inconsistency between the TSF Registry Rules, RFP, or contract, and the IESO market rules, any legislation or regulation, the terms in the market rules, legislation, or regulation as applicable, govern.