A-kasse - Unemployment insurance
As opposed to all other forms of social security in Denmark, unemployment insurance is voluntary. Thus, you are not automatically insured against unemployment.
What is an "a-kasse"?
The Danish word "a-kasse" is an abbreviation for "arbejdsløshedskasse" and means unemployment insurance fund.
Some of the A-kasser will only accept new members from one or certain professions while others are interdisciplinary (=open for anyone). In danish the word for interdisciplinary is "tværfaglig".
So no matter what your work is, or if you are student, what your study is, you can always become member of one of the 10 "tværfaglige" A-kasser in Denmark. We have a list here of the 10 "tværfaglige" A-kasser.
When you join (become a member of) the a-kasse, you are guaranteed an amount of regular income if you become unemployed.
So the a-kasse can give you time to look for the right job, pay your bills - and in fact help you to find a job.
If you only want to secure your income (and don't want membership of a Union, se below) you could with no risk just choose the cheapest A-kasse, because your unemployment benefits is secured and paid by the Danish State no matter what A-kasse you choose.
An "A-kasse" is a private association, but the most of the money you pay for membership, is transfered by the A-kasse to The Danish State.
If you become unemployed, your unemployment benefits ("dagpenge") will be paid by your A-kasse, but the A-kasse will get the amount refunded by the Danish state.
Many Danes are in addition to membership of an A-kasse also member of an Trade Union.
Also Trade union membership is (like membership of an A-kasse) voluntary in Denmark, but in 2023 about 68% of danish workers at all levels of employment are members of a Union.
As a member of a Union you get access to some services (especially legal help with issues relating to being an employee i.e sickness, being laid off, pregnancy etc.)
Traditionally many danes have choosen to be member of an Union that covers their professional field.
In Denmark we have the traditional Trade Unions like 3F, Dansk Metal and HK, but the last 10-15 years the so called "Yellow" Unions have experienced a rise in number of members.
Both A-kasse membership and membership of a Union provides a great opportunity to establish personal and professional networks, as they both offer several social and professional activities.
Unions and unemployment funds are two independent instances. So you can easily be a member of an unemployment fund without being a member of a union.