Adapted from The Bottom Line: Six Myths About the Financial Impact of Public Charter Schools by Matthew Arkin and Bryan C. Hassel
Myth 1: Charter Schools Rob Money from the Public Schools.
Charter schools are public schools and they operate in the interest of public school students. The money they receive, therefore, is not being “drained” from public education at all. Instead, it is moving from one public education provider to another. Charter schools can also bring new resources into public education. The U.S. Department of Education, through the Charter Schools Program, provides grants for the planning, development, and initial implementation of charter schools. This additional funding would not be available to a community otherwise.  Furthermore, charter schools are often successful with private fundraising, bringing even more dollars into public education. In the state of Illinois, for every $10 of public funding charter schools received, they brought in another $1.78 in private funding in 2002-03, totaling $11 million. 
Myth 2: A Dollar Received by a Charter School deals a Dollar’s Worth of Fiscal Pain to the School District.
Because charter schools typically receive less than full funding,  school districts are actually left with more money per pupil when a student moves to a charter. Suppose a school district receives a total of $50 million with 5,000 student from the State of California. Without a charter school, the per-pupil funding would be $10,000. When a charter school opens in the same district, the charter school would receive $9,000 per pupil, because the State of California expects the charter school to operate with less money. If the charter school serves 500 students, the State would only allocate a total of $4.5 million to the charter school, given the $9,000 per-pupil funding. After the State has redirected $4.5 million from the district to the charter school, the district will have total $45.5 million for the remaining 4,500 students. The new per-pupil funding for the school district is now $10,111. As a result of the charter school, the district’s per-pupil funding has gone up by $111. A March 2006 analysis by the New York Charter Schools Association corroborated this theoretical calculation. The association found that district per-pupil spending had increased by 37 percent in Albany and 25 percent in Buffalo since charter schools came into existence.