According to the Corp. tax law article No.112 and Income tax law article No.160, every business owner need to keep accounting data properly, and a corporation need to keep his accounting data in a double entry bookkeeping system, as well as an individual business owner who's previous year's sales revenue was more than 75mil.won but it depends on his or her industry involved.
But all of licence-holder like a lawyer, CPA, medical doctor and scrivener should keep the book in a double entry bookkeeping(복식부기) system regardless of a previous sales revenue as an exception.
If violated, the fine is 20% of the tax payable calculated.
For an individual business guy who's previous revenue was less than 75mil.won, he or she still need to keep the accounting data in a simplified bookkeeping(간편장부) system if the previous sales revenue was more than 24mil.won.
For more details, please send me an email to email@example.com, Gooday!