Enforcement Rules of the National Health Insurance Act Article 58

The premium payable by the beneficiary, who subscribed to Insurance more than once, shall be calculated and paid in accordance with Articles 17 and 18, and Article 11 of the Act. Where the premium is paid for twice, the group insurance applicants or the insured may apply for reimbursement within five years after the date on which the premium was paid for twice, or otherwise the application shall be rejected upon expiration.After being verified by the Insurer to be true, the premium subject to reimbursement pursuant to the preceding paragraph shall be balanced when calculating the premium of the following month.