Some 50,000 people in the Netherlands still have a passport without a valid date of birth because it is unclear exactly when they were born, the AD says on Monday.

Not having a full date of birth makes it impossible to calculate when people should get the state pension, or to book flights and get a government approved digital signature or Digid, the paper points out.

The problem is particularly acute among immigrants from countries without a rigid system for registering births, the paper says.

To tackle the problem, in 2014 the Dutch state introduced a fictitious birth date for all refugees who don’t have a complete birthday: January 1 for people born in the winter and July 1 for those in the summer months.

However, the AD found that many local councils are not making people aware that they can change their passports and only get a handful of requests for change a year.