Individuals reported a combined 5.1 trillion won worth of financial assets, while 563 corporations held deposits of 56 trillion won.

Hong Kong was the No. 1 location for overseas accounts held by South Korean companies, followed by Macao and China, the NTS said.

For individuals, however, the United States was the most popular country for financial investment.

Under the country's tax law, Korean nationals who have more than 1 billion won in foreign financial accounts are obliged to report to the authorities every month. Otherwise, they will be fined up to 20 percent of their undeclared money.

Since 2011, when the government started earnestly clamping down those that do not disclose overseas accounts, the NTS has discovered 249 people who tried to conceal overseas accounts and ordered them to pay 71.1 billion won in fines. (Yonhap)