You live and work in Korea. For some reason, you may need a certificate of your income in Korea. You can even get the salary certificate in English and Korean. The proof of income is called “소득금액증명” in Korean.
How to get the certificate?
Visit your local NTS (NTS stands for National Tax Service and is the official governmental tax organization) office to get the English or Korean document. There are many local tax offices in Seoul, so you could go any local branch offices of them. It is fine to go anywhere based on your convenience. Local tax offices are called “세무서” in Korean. Follow the link to find them in Naver. (How to use Naver in English.) When you get there, find the Public Service Center(민원실), and tell them that you need the income tax certificate (소득금액증명) for whichever year you need it.
What documents should I bring?
Prepare your government issued ID, such as your passport, or Alien Registration Card (ARC) by the Korean government. They would not ask for the document, but if you run your own company you could bring your company’s certificate of business registration to prove that you are the CEO of the company (사업자등록증) in Korean to public servant at NTS local office. If you are a CEO I recommend you to visit them by yourself, otherwise your colleagues need to bring more documents such as power of attorney and more.
What does the certificate of income look like?
You can download the file from the NTS website or look at the image below.