My math was off but I have friends in Ridgewood (really anywhere in Bergen County property taxes are outrageously expensive), Rye, Katonah, Scarsdale that pay over of $20k annually in property taxes. Heck even in my neck of the woods $12-15k annually is the going rate.
$12k or so isn't uncommon here but $20k? What size house do they have? Sounds like it must be quite large and a nice size piece of property. Damn.