The Dutch Ministry of Finance published the written guidance (leidraad meldingsplichtige grensoverschrijdende constructies) with details on how to interpret and apply the Dutch implementation of EU Council Directive 2018/822 (DAC6).
The first version of the guidance is published here https://www.officielebekendmakingen.nl/stcrt-2020-34991.html (in Dutch) and will be updated from time to time.