If you frequent education blogs, you may have run across the following accusation: "Charter schools enroll students at the beginning of the school year, get the state money, and then kick some kids out while keeping the state money for the rest of the school year, and meanwhile those kids go back to the public schools, which don't get funded for having those kids."

 I can't say that this has never happened, but the funding formula implied by this accusation seems unlikely and probably apocryphal. But I can point to an instance where essentially the opposite occurred, according to the Washington Post:

Traditional [DC public] schools are funded each spring based on projected enrollment for the coming academic year. The system overestimated its population for the 2011-12 school year by more than 2,000, meaning it received about $18  million for new students who did not turn up in the annual audited count. School leaders were not asked to return the funds.

Charter schools are financed in quarterly installments based on actual head count. If enrollment dips during the year, payments are reduced. If enrollment rises, payments increase. Charter educators say the dual standard makes no sense. “I don’t know how you can see that as anything but unfair,” said Washington Latin Head of School Martha Cutts.