The Gongbeob system, a new taxation system which was introduced to the Joseon society during King Sejong’s reign, has been believed by scholars and the public for a very long time as a reasonable and advanced taxation system. It was also heralded as one of the greatest achievements of King Sejong, and has been described along with terms such as ‘Six levels of Land, Nine levels of Weather and Yield,’ in Middle and High school textbooks. Yet why and how Sejong launched this particular system, and what was the result and effects of it, were never sufficiently discussed. Only the reputation of it being ‘reasonable’ has prevailed for a long time, while elements of the time itself which should be understood to properly define this new Law’s nature and meaning have remained poorly examined.<BR> So, discussed in this article is why this new Gongbeob Law was devised, how it was implemented, and what were the results and meaning of such implementation. Unlike how it actually ended up being, the Gongbeob system King Sejong first envisioned was a taxation system designed to collect only “pre-fixed” amounts, and not “changeable-due-to-conditions” amounts. But in the process of finalizing the general outline of the new system, governmental officials opposed such original idea, and King Sejong had no other choice but to maintain the age-old principle that had been upheld in the previous tradition of ‘Assess first, then Levy Tax,’ and incorporate the usual practice of collecting different amount of taxes according to the weather and yield of that year. As the very nature of the new law drastically changed, it was decided to also categorize statuses of the land more meticulously, and that was how the aforementioned ‘Six levels of Land, Nine levels of Weather and Yield’ came to be the most well-known characteristic of the new law.<BR> King Sejong originally wanted to secure a fixed amount of fiscal income by this new Gongbeob system to battle the monetary problems of the government. But as he was not able to do so, he also initiated the Institution of Land for State Usage(國用田制), and tried to yet again solve the income problem. However, Sejong’s original objective continued to resonate with future kings, and later, all resources which were slated to be taxed -including all the collected land taxes- were eventually registered on the document called ‘Gong’an.‘One may say, the final format of Gongbeob was nowhere near the law Sejong wished it to become, but the intention and aim later had an enormous impact on Joseon’s fiscal policy and structure nonetheless.