Each year, the IESO oversees and reconciles more than $14 billion in funds from the electricity market by collecting funds from buyers; transferring funds to sellers; collecting transmission tariffs; as well as settling the transmission rights market.

The IESO places the highest importance on maintaining the reliability of these systems and processes as well as ensuring the complete accuracy of these core functions.

This section explains the mechanics of IESO metering and settlements processes, how market participants transact with the IESO, and how specific charges are calculated.

Reading and Collecting Meter Data

Central to the IESO settlements systems is the meter data management system (MDMS), which is responsible for collecting raw data from over 1800 metering installations around the province. The meters measure and record all energy injected and withdrawn from the grid for each five-minute interval. The data undergoes the validation, editing and estimation (VEE) process before it is ready for settlement.  

IESO market participants can access their meter data on the IESO Private Reports Site.

Market Participant Invoicing​

Market participants receive a daily statement for each trade day, and a monthly invoice on their private reports site. Market participant invoicing involves the following steps:

Preliminary Settlement Statement

The preliminary (first) statement for each trade day is available ten business days after each trade day. If participants have any disagreement with the statement, they can submit a Notice of Disagreement to the IESO using Online IESO  within four business days of receiving their preliminary statement. 

Final Settlement Statement

The final statement for each trade day is available ten business days after the preliminary statement is available.


Finally, invoices are available once a month, ten business days after the end of the calendar month. The invoice is based on final settlement statement data for the first half of the month and on preliminary settlement statement data for the last half of the month. Preliminary settlement statement issues will be corrected on the final settlements statement on the following months invoice.

Participants can log in to view their statements and invoices on the IESO Private Reports Site.

Key settlement and payment dates can be found in Market Calendars.

Learn how the different charge types on your bill are calculated via IESO Charge Types and Equations.

Transferring Funds

Market Participants are required to pay their IESO invoice within two business days of receiving the invoice. Suppliers will receive their funds within four business days of receiving their invoice from the IESO.

More Inside Settlements ​

Global Adjustment

This section explains how the global adjustment is calculated and charged on based on the type of customer.

Find the Estimated, and Actual Global Adjustment rates charged to Class B customers plus information for Class A customers on tracking demand peaks.

Learn more

Guide to Electricity Charges

​This section provides an explanation of the different possible types of electricity charges participants may see on their bill.

Learn more

Price Bias Adjustment Factor

Find a list of the current price bias adjustment factors used to calculate real-time import and export failure charge as well as the day-ahead linked wheel failure charge.

Learn more