Overbilling (sometimes spelled as over-billing) is the practice of charging more than is legally or ethically acceptable on an invoice or bill.
[3] Overbilling can occur when larger institutions or governments create errors in their calculations of how much various individuals may owe.
[6] Overbilling clients can constitute an example of breach of contract and result in fines, lawsuits, or prison time.
[9] Some individuals that have been convicted of overbilling were done so under the charge of mail fraud, or under the False Claims Act in the United States.
[11] Overbilling is a part of many fraud audit infrastructures employed by large companies.