Press Release

Regarding an Error in Cost Calculation in the Notification of Changes to the Specific Retail Supply Terms and Conditions

September 10, 2026
Chubu Electric Power Miraiz Co., Inc.
Chubu Electric Power Co., Inc.

Chubu Electric Power Miraiz Co., Inc. (hereinafter "Chubu Electric Power Miraiz") decided on February 6, 2024, to revise the electricity rates applicable to customers under the Specific Retail Supply Terms and Conditions (Note 2) effective April 1, 2024, in light of changes to the Transmission and Supply Terms and Conditions (Note 1) made by Chubu Electric Power Grid Co., Inc. and others. Accordingly, Chubu Electric Power Miraiz filed a notification of changes to the Specific Retail Supply Terms and Conditions with the Minister of Economy, Trade and Industry (Press release issued on February 6, 2024; hereinafter "the Subject Notification").。

We hereby announce that it has come to light that there were some errors in the cost calculations used to determine the electricity rates in the Subject Notification (hereinafter "this matter").

As a result of this matter, customers who have entered into contracts with Chubu Electric Power Miraiz under the Specific Retail Supply Terms and Conditions on or after April 1, 2024, have been paying electricity rates that are higher than they should be (10 yen per month for an average household (Note 3)).
We are currently exploring ways to promptly correct the rate based on the erroneous cost calculation to the correct rate and to refund the excess electricity charges to the affected customers as soon as possible. Chubu Electric Power Miraiz will provide another announcement as soon as the specific implementation details are finalized.

We sincerely apologize for any inconvenience this matter has caused to our customers and all other stakeholders.
(Note 1) Chubu Electric Power Grid Co., Inc. and others submitted an application to the Minister of Economy, Trade and Industry for approval of the Terms and Conditions for Transmission and Supply, in accordance with the Electricity Business Act, to prepare for the introduction of generation-side billing starting in April 2024, the revision of transmission charges due to mid-term adjustments under the revenue cap system, and the revision of other supply conditions. This application was approved on January 17, 2024.
(Note 2) These stipulate the supply conditions for electricity rate plans established prior to the full liberalization of the retail electricity market, such as the volumetric lighting plan and low-voltage power plans.
(Note 3) A provisional figure calculated based on a cost amount that was incorrectly calculated.

1. Background

December 2023–	Chubu Electric Power Co., Inc. (hereinafter "Chubu Electric Power") calculated the costs used as the basis for electricity rates in the relevant filings and shared the data with Chubu Electric Power Miraiz Co., Inc.
January 2024–	Chubu Electric Power discovered that there were some calculation errors in the costs used as the basis for the electricity rates in the subject notification; however, executives failed to recognize these as serious errors, and no corrective measures were taken Chubu Electric Power Miraiz submitted the subject notification (effective April 1, 2024)
June 2026–	While Chubu Electric Power was reviewing the cost calculations used in the subject notification in preparation for a future notification regarding changes to the Specific Retail Supply Terms and Conditions, it discovered partial errors in the calculations made in 2024. Consequently, both Chubu Electric Power and Chubu Electric Power Miraiz began an investigation into this matter and discussions regarding the refund of the affected charges During the investigation, additional calculation errors were identified beyond those recognized as of January 2024 This matter was made public (today).

2. Overview of Cost Calculation Errors

Regarding the total change in power generation costs over the three-year period beginning in April 2024 due to the introduction of generation-side billing, the company had calculated a cost increase of 50.1 billion yen at the time. However, the correct calculation shows a cost increase of 47.4 billion yen, meaning 2.7 billion yen was overstated.

Correct	Incorrect	Difference	Items with Calculation Errors
+47.4 billion yen	+50.1 billion yen	-2.7 billion yen	Omission of annualizing monthly discount amounts, etc.

3. Customers Eligible for Electricity Bill Refunds and the Scope of the Settlement

Due to an error in the calculation of the cost data used as the basis for electricity rates in the relevant filings, the cost was overstated. Consequently, electricity rates for contract types subject to the Specific Retail Supply Terms and Conditions (Note 4) (hereinafter "Eligible Contract Types") were set higher than they should have been, resulting in eligible customers paying more than they should have for their electricity bills.
We will calculate the settlement amount for each individual contract account and refund the excess electricity charges paid.

Eligible Contract Accounts and Customers	Number of Contract Accounts 5.009 million (Note 5) (As of August 2026)	Customers who have (or had) a contract with Chubu Electric Power Miraiz for any of the applicable contract types on or after April 1, 2024
Settlement Amount	Total amount: Approximately 1.2 billion yen	Estimated Monthly Settlement Amount for Eligible Customers (Note 6) Maximum: 152 yen Minimum: 0 yen (Note 7) Average Household Model: 10 yen (Note 8)

Eligible Contract Accounts and Customers

Number of Contract Accounts
5.009 million (Note 5)

(As of August 2026)

Customers who have (or had) a contract with Chubu Electric Power Miraiz for any of the applicable contract types on or after April 1, 2024

Settlement Amount

Total amount: Approximately 1.2 billion yen

Estimated Monthly Settlement Amount for Eligible Customers (Note 6)
Maximum: 152 yen
Minimum: 0 yen (Note 7)
Average Household Model: 10 yen (Note 8)

(Note 4) Flat-Rate Lighting, Metered Lighting A, B, and C, Temporary Lighting A, B, and C, Public Street Lighting A and B, Public Street Lighting (Supplementary Provisions), Low-Voltage Power, Temporary Power, Agricultural Power A and B, Agricultural Power (Supplementary Provisions), Agricultural Lighting (Supplementary Provisions), Late-Night Power (Supplementary Provisions)
(Note 5) Number of contract accounts for eligible contract types as of August 2026. Contract accounts for eligible contract types that were terminated on or after April 1, 2024, are also eligible for electricity bill refunds; however, the number of these accounts is currently under review and is not included in the figures listed here.
(Note 6) A provisional estimate based on a cost amount calculated in error.
(Note 7) Even for contract units eligible for an electricity bill refund, if the calculation results in a refund amount of less than 1 yen, no refund will be issued.
(Note 8) Based on the "Volume-Based Lighting Plan B, 30A" with a consumption of 260 kWh.

4. Causes and Key Measures to Prevent Recurrence

Causes	Key Measures to Prevent Recurrence
Check System
Lack of knowledge and experience among claim calculators and reviewers Claim calculators and reviewers did not have a sufficient understanding of the system, and the reviewers' oversight function was not fully effective.	Strengthening the Calculation and Review System We will establish a system that ensures both the quality and quantity of personnel—including by bringing in staff well-versed in the operations—and enables tasks to be performed with a thorough understanding of the system's details and calculation logic.
Reporting System
Lack of awareness regarding the inconvenience caused to customers Although there was an impact on the retail rates actually paid by customers, the severity of the situation was not fully recognized.	Improving understanding of the importance of performing duties correctly Through training using this specific case and the Code of Conduct, foster an understanding of how one's own work affects customers and cultivate an awareness that accuracy is the top priority in these tasks. Implement measures to broaden perspectives and promote cross-functional collaboration through personnel exchanges. Foster an organizational culture that heightens sensitivity to errors and failures and ensures prompt reporting Through regular awareness campaigns and discussions, heighten sensitivity to errors and failures and establish a shared understanding that they must be reported promptly, regardless of the magnitude of their impact. Establish rules for the exchange of critical information regarding reported figures and for reporting errors Make reporting to the head of the responsible department mandatory, regardless of the amount or scope of the impact. Clarify the reporting structure and the decision-makers responsible for judgment in the event of a serious incident. Conduct reporting using methods that leave a record, such as written documents or email.
Inadequate decision-making rules and low awareness regarding major incidents It was unclear up to which department or executive level reports should be made, and who was responsible for determining whether corrections were necessary or whether a report to the regulatory authority was required.
Inadequate management of audit trails regarding reporting and decision-making Since the sharing of important information and decision-making relied primarily on verbal communication, no records were retained that could verify the content of reports or the basis for decisions.

5. Next Steps

We are currently exploring ways to promptly correct the rate based on the incorrect cost to the correct rate and to implement measures as soon as possible to refund the excess electricity charges to customers who were overbilled. Chubu Electric Power Miraiz will provide another announcement as soon as the specific implementation details are finalized.

Back to list