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

The TSF Registry is now live. For full details and how to register, please refer to the Registry section below.

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 is available on the TSF Engagement page.

The IESO will endeavour to schedule the next engagement session for October 2025. 

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

TSF Registry

Stakeholder and Community Engagement​

Learn more about upcoming sessions and engagement opportunities here.

Subscribe for Updates

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

TSF Documents

TSF Registry

The IESO is pleased to launch of the TSF Registry, marking a significant milestone in advancing competitive transmission procurement in Ontario.

The TSF Registry represents the first step in implementing the TSF and will enable transmitters to participate in future IESO competitive transmission procurements. The registry will help identify eligible transmitters to ensure a pool of experienced and capable proponents is in place—allowing procurement processes to move forward efficiently as transmission projects are identified.

For full details on the TSF Registry and how to register, please refer to the Registry Rules below.

To begin your application, follow the TSF Workspace Instructions provided.

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

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.