The attorney identifies an amount of work that the case will require and calculates a reasonable fee based on the time and effort involved. If the attorney spends less time on the case than expected, he may keep the excess fee amount, unless he and client agree otherwise. However, if the attorney charges a flat fee and the case requires more time and effort than originally expected, the attorney may not later demand more money. The attorney and client may agree that these fees be paid periodically or in a lump sum at the end of the case. The time that an attorney charges for legal work is called billable time, or billable hours.
Hourly rates vary according to the attorney's expertise and experience.
Some critics have argued that hourly rates discourage quick work and expedited resolutions. Before agreeing to payment of an hourly rate, prospective clients should ask for a written estimate of the number of billable hours that the attorney anticipates will be necessary for the case. For example, a typical contingent fee might be about one-third of the recovery in an action for personal injury. Attorney's use a contingent fee when the client seeks money damages. Contingent fees cannot be used in divorce cases, child custody cases, and criminal cases.