The National Register (Folkeregisteret)
If you are going abroad for less than 6 months and you maintain your accommodation in Denmark, you might be able to keep your registration in Denmark. Please check with the Citizens Services (Borgerservice) in your municipality what rules applies to you.
If you do not maintain your room / if you go abroad for more than 6 months, you will need to inform the National Register (Folkeregisteret) in your municipality. When you return to Denmark you will need to register again.
Please visit borger.dk (DA) and and lifeindenmark.borger.dk (EN) for more information on what applies to you.
Taxation
A study period or internship abroad might affect your tax situation in Denmark. For more information, visit the Danish Tax Administration (SKAT).
Non-Danish citizens: check your residence permit
If you are a non-Danish citizen, we strongly recommend that you check up on whether or not your residence permit (regardless of type) allows you to leave and return to Denmark, or whether you need to apply for a new one.
This is important regardless of your citizenship (EU/non-EU) and duration of exchange stay.
If you are in doubt, please contact the authorities directly - you can find the contact information on newtodenmark.dk.