You did understand that they shoved the main compliance effort onto the banks?
So if you want to claim it's a monster IT project on the banking side (details in here), ok, but the governmental side is quite light.
Figuratively speaking, think of it as the banks sending their country's central tax authority (in Germany: to the Bundeszentralamt für Steuern) already addressed envelopes with tax data, so the central tax authority just has to forward that envelope to the address (= foreign tax authority) written on it.
Such an EU-wide system has already been in place from 2005 to 2015, through the implementation of the EU savings directive, and the German interface was the Bundeszentralamt für Steuern, so they have experience in this.
This EU-wide system has now been replaced by the OECD's worldwide AEOI (Automatic Exchange of Information) standard we have been talking about all this time.
For details of this change-over, please read this: http://www.lexology.com/library/detail.aspx?g=02ab29d9-12c0-42cd-b363-9dcca24a4064
Under AEOI, the following data will be reported to your country of residence, no matter whether the account holder is a person or a company (sources p. 74-75 of the Implementation Handbook and p. 3 in here):
income from the sales of shares/mutual funds/...
income from insurance contracts
the balance of the account/shares portfolio/insurance contract on 31. December of each year