Yes, it is possible to make purchases on arrival Terminal 1 (including transfers). However, you must show your valid boarding pass when making your purchase. Please note that it is not possible to access the shops at certain departure halls.
Can I also make purchases before customs?
GASSAN Schiphol can only be found on the airside. So you can only make purchases when you are going to fly.
Do I have to declare the purchased goods when I return to the Netherlands?
You can find the rules for this on the website of the Belastingdienst. We advise you to read the applicable provisions carefully.