Legal basis: Article 102 of the Detailed Rules for the Implementation of the Frontier Health and Quarantine Law of People's Republic of China (PRC). Anyone who applies to live abroad for more than 1 year must hold a health certificate issued by the health and quarantine organ. The exit and entry administration authorities of China citizens shall go through exit formalities with the health certificate issued by the health and quarantine organ. China nationals who have lived abroad for more than 1 year must declare their health status to the health and quarantine organ when they enter the country, and go to the nearest health and quarantine organ or hospital at or above the county level for health examination within 1 month after they enter the country. The public security organ shall handle the relevant formalities with the health certificate. A copy of the health certificate shall be submitted to the health and quarantine organ at the original port of entry for the record. Employees in China who take internationally accepted means of transport shall hold health certificates issued by health and quarantine organs or hospitals at or above the county level. The items and format of the health certificate shall be uniformly stipulated by the General Administration of Customs, and the validity period shall be 12 months.