I can't figure out what exactly is happening but my empire suddenly went to 100k deficit in a single turn with no reasoning.  I checked the Money tool tip in the corner and it shows that suddenly my military is requiring 73k upkeep a turn and district upkeep is over 23k a turn and my alliance upkeep jumped to up to 10k per turn.  None of those numbers are anywhere close to correct, I can manually add all my military upkeep and it's not even close to that.  This is my first game so far so the difficulty settings are still on the tutorial levels.  The two saves show normal expenditures and then the sudden jump.  auto-save 266.ctrauto-save 267.ctr

ceepee wrote:

I see this happen too. The reason it seems to be happening for me, is when I store 8 multirole fighters on a base or aircraft carrier. when I reduce the number back to 7, the deficit also goes back to normal.(might also work for cruise missiles)

Can you verify that this also happens with your save? If anything it's a very clear and singular cause.

You are right when aircraft reach 8 unit it's upkeep is increased astronomically...