Chubu Electric Power Group announced on September 10, 2026, that it has overcharged approximately 5 million electricity customers a total of ¥1.2 billion due to calculation errors in power generation costs, according to NHK. The overcharges have been occurring since 2024 and affect contracts across the company's service area, which primarily covers central Japan including Aichi, Gifu, Mie, Shizuoka, and Nagano prefectures. The utility company, one of Japan's major regional power providers, discovered errors in how it calculated the base costs for electricity generation. These miscalculations resulted in customers being charged more than the legally permitted rates under Japan's electricity pricing regulations. The error affected approximately 5 million contracts, making it one of the largest billing mistakes by a Japanese utility company in recent years. According to reports from NHK and Yahoo Japan Business, Chubu Electric has committed to refunding the overcharged amounts to affected customers. The company stated it will return the full ¥1.2 billion to customers who were impacted by the billing errors. This represents an average overcharge of approximately ¥240 per affected contract, though individual amounts will vary depending on usage patterns and contract types. For foreign residents living in Chubu Electric's service area, this announcement is particularly important as many expats may not have seen news coverage in Japanese media. The overcharges began in 2024, meaning customers who have lived in the region for the past two to three years are likely affected. Both individual household contracts and business contracts fall under the scope of this refund program. The billing error stems from mistakes in calculating the company's power generation base costs, which are used to determine the regulated portion of electricity rates in Japan. Japanese electricity pricing operates under a complex system where certain cost components must be approved by regulators, and companies can only charge customers based on these approved calculations. When Chubu Electric miscalculated these foundational costs, the error cascaded through their entire billing system. Chubu Electric has not yet announced the specific timeline or method for processing refunds. Customers should expect to receive official communications from the company in the coming weeks detailing how refunds will be distributed. Based on similar cases with other Japanese utility companies, refunds are typically applied as credits to future electricity bills or issued as direct bank transfers to the account used for bill payments. Expats who have moved away from Chubu Electric's service area but were customers during the affected period (2024 to present) should pay particular attention to any forwarded mail or contact the company directly to ensure they receive their refund. Those who have already returned to their home countries may need to provide updated contact information and bank details to receive payment. This incident highlights the importance of foreign residents understanding their utility contracts and rights as consumers in Japan. Japanese law provides strong consumer protections, and utility companies are strictly regulated. When errors occur, companies are legally obligated to make customers whole. Customers with questions or concerns about whether they are affected should contact Chubu Electric's customer service center. While English-language support may be limited, the company is legally required to process all legitimate refund claims regardless of the customer's language abilities. Expats who need assistance can also contact their local consumer affairs center (消費生活センター), which often provides multilingual support for foreign residents dealing with utility and consumer issues.