Maintenance contracts are becoming more and more popular to the owners of complex and critical items as maintenance through contracts reduces upfront investments in infrastructure, expertise and specialised maintenance facilities. In recent years, maintenance contracts have received significant attention due to increased profits for the service providers and reduction of risk for owners through expert services provided by the service providers. To make maintenance contracts more effective, there is a need to develop mathematical models and understand future costs that could be built into the contract price. In this paper, a conceptual model is developed for estimating cost of outsourcing maintenance of complex and critical asset/equipment taking into account both corrective and preventive maintenance as servicing strategies.