Matthew Arkin and Bryan Hassel [2.33MB PDF]:

School districts across the country are having financial problems, and charter schools are increasingly getting blamed. Charters are accused of taking money from “the public schools,” although they are public schools themselves. Charters are even taking the blame for rising taxes. These assertions certainly paint a clear picture of some district administrators’ feelings about charter schools – but they don’t tell the full story.
In fact, high-quality public charter schools have positive financial impacts for communities that more than offset the obvious and immediate revenue losses to districts. Accurately measuring the financial impact of charters requires looking at not only the revenue shifts for the school district but also these benefits to the broader community.