Can you claim brokers fees e.g., market data subscription, as asset management costs (Vermögensverwaltungskosten)?
Not as a regular private investor. Perhaps if you declare yourself as a professional, which would involve some other pain however.
You are allowed to deduct 3 promille (=3/1000) of your assets under management as costs. This you can do in the section "deductions" under "costs for mgmt of private wealth"
Thanks for the answer. I guess in German 'Easy Tax Programm' that will be under: 'Möchten Sie zusätzliche Vermögensverwaltungskosten geltend machen ?'