The primary source of income was land taxes, but there were also customs fees and tolls for roads, as well as fines levied on lawbreakers. While we don’t see an example in the text, there were restrictions for smallfolk to use the lord’s facilities and pay a portion for the use, particularly for grain mills. The extra milled grain could be sold to places where grain was scarce, due to blight or bad soil.
However, several families are impoverished despite being noble in the setting. The Corbrays and the Westerlings come to mind, as do the Tarbecks, whose castle, Tarbeck Hall, was crumbling despite their old and impressive pedigree. Like the Tarbecks, the Conningtons might marry into a wealthy family, or come up with an idea to reverse their flagging fortunes. JonCon’s landing, however, is putting a halt to that.
Thanks for the question, Anon.
SomethingLikeALawyer, Hand of the King
In the case of the Conningtons, since they’re right on the coast btw Storms End and the southern half of the Stormlands, they probably charge tolls on passengers crossing their land, since there’s prob. a good bit of traffic on that route.