South Korea’s government is hitting the country’s cryptocurrency exchanges with massive tax demands, in its latest attempt to rein in the booming and volatile sector.

According to a finance ministry official, cited in a Yonhap report on Monday, South Korean cryptocurrency exchanges will this year need to pay 22% corporate and 2.2% local income taxes on last year’s earnings by the end of March and April respectively, if they had an annual income of over 20 billion won ($18.8 million) during 2016.