The pension scheme is tax deferred meaning that your employers pension contributions are not taxed when paid into the scheme.
Your own contributions paid into the scheme are tax deductible. You can withdraw the pension funds upon retirement age and the pension will then be taxed in Denmark.
It is possible to withdraw the pension funds before the age of retirement, but you will have to pay a duty of 60%.
Any yield accumulating in the scheme will be taxed annually in the scheme by a flat tax of 15.3%. This is called PAL-tax. If your full Danish tax liability is later terminated, or you become tax treaty resident in another country, you are not required to pay PAL-tax on your Danish pension. You will have to apply the Danish tax authorities for your pension scheme to be exempted from PAL-tax withholding.
This pension scheme is also known as a 53A savings scheme. This type of scheme is seen almost exclusively as employer-administered schemes as they are not subject to any special tax treatment and therefore rarely makes sense on a private basis.
Contrary to the ordinary scheme, the pension contributions are taxed upfront. Your own contributions are paid from post-tax funds, and you can therefore withdraw the money according to the conditions for the pension scheme without any further Danish tax consequences.
The yield or interest on a 53A pension scheme will be taxed annually as capital income with a marginal rate of 42%, and losses can be carried forward to future tax years but cannot be offset against other income (source limited).
Once you move to Denmark and have a foreign pension scheme you will have to fill out the declaration L. This declaration is used to inform the Danish tax authorities about your foreign pension schemes, the pension balance each year, and annual payments and returns on the pension scheme.
Whether you have to file Declaration L each year depends on the type of pension/insurance etc.
During your stay in Denmark, the main rule is that you are covered by Danish social security, unless you are here on an assignment or retain a residence abroad whereas exceptions may apply.
The ruling about social security is primarily covered by EU regulation.