The Social Security Agreement between the United States and Denmark, which was ratified on October 1, 2008, ensures that a person will not lose his right to U.S. Social Security or Danish Folkepension when moving between the two countries.
In the United States the application for Danish Pension must be submitted through the local Social Security Administration (SSA) office. From there the application will be forwarded via the SSA Office of International Operations to the Danish Pensions Agency. When the Pensions Agency has processed the application, the applicant will be notified by the local SSA office.
The Social Security Agreement is also of benefit to U.S. and Danish companies as it makes it easier to transfer employees between the two countries. The agreement makes it possible for the employee to remain part of his home country’s social security system without interruption while working in abroad.
Please see the information from both the Danish Pensions Agency and the U.S. Social Security Administration her:
Handbook from SSA (Social Security Administration).
Information from the Danish Pensions Agency (in Danish only).