Real estate tax is also somewhat unpredictable year to year (except that it rarely goes down), and can be a large part of your monthly payment. We got hit with a 21% increase in taxes this year because the town voted to rebuild the high school and the main road.

Luckily, at least, we don't have an HOA. Well, actually, we technically do, because we have a shared driveway with three houses on it, and legally here shared driveways are required to have an HOA. But all three of us despise HOAs, so it doesn't have any money, rules, meetings, or do anything. It's just on paper only. We have informal meetings to sort it out when the driveway needs maintenance. After just a couple meetings we figured out that meeting first, alcohol second is the correct order.