In which country a person is insured for national insurance is regulated within the EU by a regulation. The main rule is insurance obligation in the country of residence, but if one works exclusively in another country, the insurance obligation lies in the country of employment.
Germany has the phenomenon of mini-jobs. For employees earning less than €450 per month, there is (virtually) no tax and contributions to pay. However, these Geringfügige Beschäftigungen (the official name for mini-jobs) give limited access to German social insurance.
A person living in the Netherlands and working in Germany in one (or more) mini-job(s) is insured in Germany under the European regulation. But Germany excludes mini-jobs from (almost) all insurance. As a result, no (or only limited) recourse to national insurance benefits is possible on either side of the border.
The CJEU recently confirmed that a person living in the Netherlands and working exclusively in a mini-job in Germany is insured for national insurance in Germany. According to the Court, the Netherlands is allowed to give these people access to Dutch national insurance anyway (this would be possible, for example, under the so-called hardship clause).
One of the cases in which the court decided this concerned Ms Franzen, who lived in the Netherlands and worked as a hairdresser in Germany. Despite the fact that her working hours were 20 hours a week, the income was so small that it fell under the mini-jobs scheme. Ms Franzen therefore fell under German social insurance and was not entitled to Dutch child benefit. However, German law excludes people working in mini-jobs from Kindergeld.
Another case concerned Mr Giessen, who lived in the Netherlands with his spouse. Because the spouse worked in Germany in a mini-job, a reduction was applied to Mr Giessen's AOW partner allowance. This was because his spouse was not insured in the Netherlands during the period she worked in Germany as part of the mini-job.