In the new tax system, there is a line-item called "crown's total income." It is the sum of revenues taxed from duchies, and an "other revenues" line, explained as "fines, etc." I have noticed that this line-item, "other revenues" or "fines, etc" is never zero, and seems very stable, such that it has been the same number in one realm I've been watching for 3-4 weeks.
I am curious where this revenue comes from, as neither realm I'm in has had any fines recently, and the sum of gold it provides is large, especially since it goes straight to the crown.