Hesse state prosecutors said Tuesday in addition to 12 searches in Hesse and Bavaria, an apartment was searched in the Netherlands.
The suspects, aged between 50 and 57, are accused of bilking the government of 53.3 million euros ($59 million) in taxes in 2008-9 through so-called cum-ex transactions where participants would lend each other shares to collect reimbursement for taxes they hadn't paid.
The funds have already been repaid by the legal successor of the Frankfurt-based investment company involved.
German authorities are conducting multiple cum-ex investigations after a Swiss bank's employee leaked documents to journalists detailing the scheme that allegedly cost European countries 55.2 billion euros.
The searches are separate from others conducted Tuesday connected to money laundering.
Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.