When I logged in today, I suddenly had a late payment on my harvester farmhouse. However I have just upgraded my house a few days ago, where I paid the taxes, and I know I had no taxes to pay for the farmhouse atm. I did however have to pay taxes for my 16x16 farm, which I had around 2 days to pay. But while the sudden "late taxes" for my harvester farmhouse appeared, the taxes I needed to pay for the 16x16 disappeared.

A huge difference in these two taxes I need to pay, is the fact that the taxes I now suddenly need to pay for the harvester farmhouse is over 100, while I only needed to pay 30 taxes for the 16x16.