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    Deferral Accounts - Rider C & DAR

    Deferral Account Adjustment Rider (“Rider C”) 

    The ISO must recover or refund through Rider C accumulated deferral account balances, which are the difference between revenues and costs incurred in providing system access service to market participants.  

    Rider C is a charge or credit that the ISO determines each quarter by examining the available recorded and forecast values, required to restore the deferral account balance to zero (0) at the end of the calendar year.

    Deferral Account Reconciliation (“DAR”) 

    The DAR reconciles variances arising from the actual costs the ISO incurs in providing system access service and the actual revenue recovered through Rate DTS. 

    The ISO typically files the DAR with the Alberta Utilities Commission on an annual basis by the end of Q2 each year. Once the DAR is approved by the Alberta Utilities Commission, the ISO financially settles the deferral account balances with market participants, which typically occurs by the end of Q3 each year.  To learn more about the DAR, register for the eLearning Course on DAR Methodology through the AESO’s Continuing Education site.

    • 2024 DAR

      Preliminary AESO 2024 Deferral Account Reconciliation Amounts [Posted: March 31, 2025]

      The AESO has calculated a preliminary estimate of a net deferral account surplus of approximately $7.5 - $12.5 million for its 2024 Deferral Account Reconciliation (DAR) application, which will involve adjustments to production years 2020 through to 2024. This amount is subject to change throughout the validation stage of the AESO’s DAR process.  

      As part of its 2024 DAR process, the AESO will be calculating the allocation of this amount to all market participants receiving system access service under Rate DTS, Demand Transmission Service and Rate FTS, Fort Nelson Transmission Service. The AESO will update distribution facility owners (DFOs) as needed, as it moves towards a final net amount and its allocation to each DFO.

    • 2023 DAR

      The 2023 DAR under proceeding 29139, was approved by the Alberta Utilities Commission in Decision 29139-D01-2024. The 2023 DAR resulted in a $5.6 million surplus, that will be settled with market participants in September 2024.

      Revised Estimate: AESO 2023 Deferral Account Reconciliation Amount [Posted: June 17, 2024]

      The AESO has revised its preliminary estimate for its 2023 Deferral Account Reconciliation (DAR) application. The revised estimated surplus is in the amount of approximately $5 – 6 million. This amount continues to be subject to change throughout the validation stage of the AESO’s DAR process.

      The AESO expects to file its 2023 DAR application with the Alberta Utilities Commission for approval by no later than mid-July 2024. Upon approval, this page will be updated to reflect the approved total amount of the 2023 deferral account surplus.

      Preliminary AESO 2023 Deferral Account Reconciliation Amounts [Posted: March 26, 2024]

      The AESO has calculated a preliminary estimate of a total surplus of approximately $11 - 16 million for its upcoming 2023 DAR application, which will involve adjustments to production years 2019 through to 2023 and is subject to change through the validation stage of the AESO’s deferral account reconciliation process. The AESO will be calculating the allocation of this amount to all Rate DTS, Demand Transmission Service, and Rate FTS, Fort Nelson Transmission Service, customers with its DAR System, and expects to file its 2023 DAR application with the Alberta Utilities Commission (“Commission”) no later than June 30, 2024. Depending on the AUC’s regulatory process timing, settlement of the 2023 DAR balances will likely occur in late 2024. 

    • 2022 DAR

      The 2022 DAR under proceeding 28293, was approved by the Alberta Utilities Commission in decision 28293-D01-2023. The 2022 DAR resulted in a $18.9 million surplus, that was settled with market participants in September 2023.

    • 2021 DAR

      The 2021 DAR under proceeding 27547, was approved by the Alberta Utilities Commission in decision 27547-D01-2022. The 2021 DAR resulted in a $9.5 million surplus, that was settled with market participants in September 2022.

    Deferral Accounts - Rider C & DAR