All citizens use the public sector in some way, and as a general principle all citizens must thus help pay for it. The tax funds are used to pay for the different expenses that Danish society has such as welfare benefits, state pension, child benefits and for public institutions such as schools, hospitals, libraries and the police.
The Danish tax system is progressive. This means that the higher your income, the more taxes you have to pay. In many other countries citizens pay less tax than in Denmark, but in return they have to pay to go to school, to the hospital, the doctor's, etc. Denmark has its own Minister of Taxation, Ministry of Taxation and its own taxation laws.