According to an article that Radio Free Asia published, since May, North Korea has been imposing different types of tax and fees on merchants who come from China to enter the Rason Special Economic Zone. The total could add up to as much as 1,000 yuan (US$147) for each such entrance. The move is considered to be related to friction in the foreign relations between China and North Korea. The article quoted comments from South Koreans that, since North Korea is facing sanctions from the international community, it is possible that it is using the imposed taxes to offset the shortage in foreign currency. However since the fee is not a small amount for small businesses owners, it might also result in a reduced traffic flow and trade activities.
Source: Radio Free Asia, June 1, 2017