A 25% cut is always taken from the UC sale. That 25% is split in half between the FC and the UC service itself. So in other words, 75% goes to the seller, 12.5% goes to the FC, and 12.5% "disappears" as it goes to Universal Cartographics.
If you're selling data to the carrier and you're the carrier's owner, obviously that 12.5% going to the carrier is still "yours", and so it feels like you only lose 12.5% instead of 25%.
24th of february 3307, DSSA The Helix, Dryman's Point
It's under 30 jumps from DSSA Nostromo to DSSA The Helix. Visited a colony of eight-legged peduncle trees on the way, wondering what researchers might draw from my data. The Helix itself is in a system, where along with peduncle trees metallic crystals can be found, a first one for me in this region. A short visit turned a two weeks break, enjoying the A class through the decks windows - tanking light far from the core!