Funds rating varies! On the record, Mentats take a Vow of Poverty. KitKat's wealthy benefactors include Emperor Gregor Vortapani and the Mentat Force Order.
Kit Kat and another graduate of the Mentat Academy on their homeworld of Mentis, Almon d’Joy, were once fairly friendly rivals in school, but Kit Kat was gifted to House Vorpadaran and particularly Danar Vorpadaran, and Almon was gifted to, well, other persons for whom his skills were more closely aligned. You see, Kit Kat, often concluded answers to problems faster by immediately discounting unethical courses of action, thus reducing the number of possible solutions to be computed. Almon took the other route, often arriving at more creative solutions, but less ethical ones. After the events of - well - a LOT, KitKat has been placed in charge of d'Joy's rehabilitation (and un-twisting away from the Dark Side).
Near the end of 12726, by Tapani Year recoging, the events of Pitch Dark transpired. This brought KitKat to the attention of Tapani Imperium's Emperor Gregor! The Emperor confiscated Kit Kat through Imperial Fiat to work on larger projects that affected the Imperium as a whole.