Kansai Electric Power said it had overcharged electricity customers by up to approximately ¥14 million ($90,000) since April 2024 because of errors in cost calculations submitted to Japan's Ministry of Economy, Trade and Industry during that month's rate revision. Up to 7.14 million accounts may be affected, mainly residential contracts, with a maximum impact of ¥1 ($0.0064) per contract each month. Municipal streetlights and agricultural facilities are also included. The company discovered the potential problem in early August while calculating how to incorporate a scheduled November 2026 increase in wheeling charges (fees for using transmission networks) into electricity rates. After reviewing earlier calculations and confirming the facts with its power transmission and distribution subsidiary, Kansai Electric Power announced the issue on the 17th. It said the discovery was unrelated to Chubu Electric Power's error and arose independently during its own work. Chubu Electric Power's group has separately been found to have overcharged customers by approximately ¥1.2 billion ($7.7 million) during the same period. Kansai Electric Power will review the impact on each account before issuing refunds and is considering refund procedures and measures to prevent a recurrence. The account count and affected amounts remain under investigation. The parallel errors at two major utilities have raised concerns about confidence in regulated rate calculations, and other companies may re-examine earlier filings as wheeling-charge revisions approach.