While under current legislation dual citizenship is already banned in principle, a number of exceptions imply that most immigrants who naturalize can retain their citizenship of origin. The same goes for many Dutch citizens abroad who voluntarily acquire another citizenship. The proposed amendment to the citizenship law aims to remove most of these exceptions which means that most immigrants who acquire Dutch citizenship by declaration or naturalization will be required to give up their original citizenship, if legally possible. Many Dutch emigrants will also automatically lose their Dutch passports when they acquire another citizenship.
The government bill in addition proposes to introduce a naturalization requirement to have a family income of at least the minimum wage and to have at least two years work experience or have some sort of professional qualification. The residency requirement for persons married or in a civil partnership with a Dutch citizen will be increased to five years, as in the ordinary naturalization procedure.
See the article on DutchNews.nl, the announcement on the website of the Dutch government (in Dutch) and the article in The Economist (Jan 7, 2012).