German authorities said they have purchased a CD containing secret Swiss bank account details of thousands of alleged tax evadors.
The south-western state of Rhineland-Palatinate said the data prompted over 200 raids nationwide against suspects in the early hours of Tuesday.
State Finance Minister Carsten Kuehl said he expects to net some 500 million euros ($654 million) as a result.
Mr. Kuehl said the data was deemed “authentic and of excellent quality” by investigators before it was purchased for 4 million euros.
German states have purchased several sets of data stolen from Swiss banks in the past to pursue suspected tax evaders.
This practice has angered Switzerland but served as ammunition for German opposition parties who object to a government-backed deal amounting to an amnesty for German clients of Swiss banks.