Students arriving from countries where paid internships are the legal default assume a similar floor applies here. It does not, and what counts as normal varies widely by sector and by whether the placement is a short orientation or a graduation internship — which makes a low offer difficult to judge on its own.
There's no legal minimum for stagevergoeding (internship allowance) in the Netherlands, which surprises a lot of internationals coming from countries where paid internships are either the default or legally mandated. Whether you get paid, and how much, comes down to the employer and, if one applies, the cao (collective labour agreement) for that sector — some cao's set a floor, most don't. In practice, unpaid internships still exist but are increasingly the exception outside a few sectors; most placements pay something, roughly €350–€550 a month for hbo (university of applied sciences) internships and €400–€600 for wo (research university), higher toward the end of that range for a full working week and for a graduation internship versus a shorter orientation placement. Treat those as a general sense of "normal," not a guarantee — a fashion or media internship might still offer little to nothing, while engineering or IT placements often pay closer to or above that range. If an offer comes in noticeably below what classmates in the same field are getting, ask your university's internship coordinator whether a relevant cao applies — study programmes sometimes have informal minimums they expect employers to respect even without a legal requirement.