I think a lot of foreigner may have a lot questions on Korean tax system and no idea how to approach to get an answer.
The below web address is an address you can visit and ask a private questions to get some very official and exact answer on your questions.
Please click it and enjoy it by yourself; https://www.nts.go.kr/eng/help/help_21.asp?top_code=H001&sub_code=HS02&ssub_code=HSB1
Korean Tax Rate
Korean tax bureau
2019FY, 1st half closing VAT
2018FY, Global Income Tax Return
2019 FY, 1st Quarter VAT Return
Corp. Income Tax Return