An element of basic services in an architect/engineer (A/E) agreement that includes an estimate of construction cost from quantity surveys and unit costs of building elements for the project. Cost estimates shall include the elements of work to complete the project, all costs and fees and taxes necessary to complete the work, plus appropriate construction estimating contingencies to cover unidentified costs necessary to complete the project. Interactive cost estimating is additional work beyond basic services in which additional design alternatives are estimated. Independent cost estimating, if needed, covers cost estimates by an independent third party contracted with the owner and used to validate cost estimates prepared by the A/E.