An assessment and determination of insurance premiums may not be made on or after the day on which two years have elapsed from the day following the first due date for payment of insurance premiums in the relevant fiscal year (meaning the due date for payment of insurance premiums pursuant to the provisions of this Act or Prefectural or Municipal Ordinance under this Act, and in cases where it becomes possible to impose insurance premiums after the due date, the day on which it becomes possible to impose the insurance premiums; the same applies in the following paragraph).
Notwithstanding the provisions of the preceding paragraph, an assessment and decision to reduce the amount of insurance premiums in the case where it is found, after an assessment and decision of insurance premiums is made, that adjustment of the applicable relationship between the insured and medical insurance laws (excluding the National Health Insurance Act) is required due to grounds not attributable to insured, may be made on or after the day on which two years have elapsed from the day following the due date of the first insurance premiums in the relevant fiscal year, until the day on which a period equivalent to the period found necessary for the adjustment has elapsed from the day following the due date of the first insurance premiums in the relevant fiscal year.