National Tax Service Thug is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

The protagonist ‘Shin Jaehyun’, was called a traitor and lost his job because he reported corruption in his company. He did not become downtrodden and set his goals on becoming a tax official, but due to his unstable family situation, he started wavering. A ‘fated encounter’ provides a helping hand to him, and for the one becoming a NTS thug in the future, holds a sword for the first time. “No matter who you are or where you are, if you are a tax evader, I will find you.”