The developers at CD Projekt Red appear to be having some fun with players of The Witcher 3 by adding an auditor NPC who will grill them about whether or not they've been making money using in-game exploits.
It's the latest in a series of tongue-in-cheek Witcher 3 updates that showcase how a developer can approach game updates as both a technical process and a sort of dialogue between themselves and their fans.
As Kotaku notes, a Witcher 3 player who purchases the game's latest expansion and encounters the newly-added taxman won't automatically be punished for exploiting the game; they can choose whether or not to be truthful in answering the NPC's questions, and the character will take them at their word.
Thus the developers at CD Projekt Red have poured time and resources into an update that acknowledges people are playing their game in unexpected ways without appearing to restrict them from doing so.
They did something very similar this summer, addressing one of these known exploits (which involves rapidly slaughtering cows in-game and selling their hides) by patching in an incredibly hard-to-kill supercow referred to as the "Bovine Defense Force Initiative."