Here's a cost that many don't think about..... Your entertainment/travel costs can go up.
Not sure your exact situation but once that last kid is out of High School, you have significantly more time and people tend to spend more one dates and other entertainment. If you are a home body that enjoys binging on 3 hours of Netflix then this might not impact you as much. But if you are someone that just spent the last 8 years going to soccer tournaments, football games and swim meets the lull in activity led to you doing more activities.
Also, your travel costs might go up if you plan on seeing them at school a few times a year.
Not sure your exact situation but once that last kid is out of High School, you have significantly more time and people tend to spend more one dates and other entertainment. If you are a home body that enjoys binging on 3 hours of Netflix then this might not impact you as much. But if you are someone that just spent the last 8 years going to soccer tournaments, football games and swim meets the lull in activity led to you doing more activities.
Also, your travel costs might go up if you plan on seeing them at school a few times a year.