Japan medical insurance reform impacts elderly investors

Japan's medical insurance landscape for seniors is undergoing significant changes following the enactment of the Medical Insurance System Reform Act in May 2026. Under the Late-stage Elderly Medical Care System, which covers individuals aged 75 and older, new rules will integrate investment profits from specified accounts into the calculation of insurance premiums and medical cost-sharing ratios. This change applies regardless of whether the individual files a tax return, meaning higher investment returns could lead to increased health and nursing care insurance premiums.

Notably, profits earned through NISA (Nippon Individual Savings Account) are explicitly excluded from these calculations. However, the system does not offer equivalent relief for investment losses; while losses can be carried forward for up to three years to offset future gains, they cannot be used to reduce social insurance premiums by offsetting other types of income.

Regarding regional variations for the 2026 and 2027 fiscal years, the national average monthly premium per insured person is set at 7,989 yen for the medical portion, plus 194 yen for the child-rearing support portion. Premiums vary significantly by prefecture due to local medical costs. Tokyo has the highest average monthly premium at 10,352 yen, while Aomori Prefecture has the lowest at 4,990 yen.