Before you arrive at Denmark and start working, it is important that you find out whether you are required to obtain a residence and work permit.
The rules vary according to nationality. Be aware that the rules will also apply when conducting voluntary or unpaid work.

Do I need a permit?

Citizens from the Nordic countries, the European Union (EU) and European Economic Area (EEA) and Switzerland are entitled to live and work in Denmark. However, if you are an EU/EEA or Swiss citizen and intend to reside in Denmark for more than three months, you must apply for an EU residence document.
Read more about EU residence document at the Danish Agency for International Recruitment and Integration (SIRI).
You can also apply for EU residence document at International Citizen Service.
If you are a citizen from a country outside the EU/EEA or Switzerland, you must apply for a residence and work permit before your enter Denmark. I If you already legally reside in Denmark, you can submit your application for a residence and work permit on newtodenmark.dk, at a Danish police station or in the Citizen Centre of the Danish Agency for International Recruitment and Integration.