Taejong's next act as king was to revise the law concerning the taxation of land ownership and the documentation of state subjects. Although many aristocrats who benefited from King Taejo's property redistribution laws, from the Gwonmun aristocrats to the members of the Sinjin faction, had managed to avoid taxation by deliberately hiding land they acquired, King Taejong's re-investigation of land ownership in 1405 put an end to such practices. With the discovery of previously hidden land, national income increased twofold. In addition, King Taejong initiated the first population survey in 1413 and ordered the documentation of family names and clans, places of birth and death, and dates of birth and death for all Korean men. All males over the age of 16, whichever class in society they occupied, were also required by law to carry wooden tablets on which their name, birth date, and other information was engraved. Many historians regard this legislation as the predecessor of the Korean resident identification and social security system. It was also effective in preventing men from evading their mandatory military service.
