In the past several games I've played all the data has said that I have a positive net income, yet the value of my treasury steadily drops. I usually haven't built any military units, so there shouldn't be any hidden costs I'm forgetting about—and besides, I'd imagine that would be displayed in the finances screen.
Unless, that is, the Soverign eats gold. Gotta get them magicks somehow.
I tried to Jing a couple images to track the contrarian treasury change, but Elemental's ALT-TAB abilities seem to be as capricious as ever. I ended up shutting it down after a minute or so of black screen and no UI load.
Debug.err http://pastebin.com/f6467044b
DxDiag http://pastebin.com/f3b897c3e