Implicit costs (also called implied, imputed or notional costs) are the opportunity costs that are not reflected in cash outflow but implied by the failure of the firm to allocate its existing (owned) resources, or factors of production to the best alternative use. For example: a manufacturer has previously purchased 1000 tons of steel and the machinery to produce a widget. The implicit part of the opportunity cost of producing the widget is the revenue lost by not selling the steel and not renting out the machinery instead of using them for production.