Conclusion: The Total Cost of Ownership (TCO) was created two decades ago to provide visibility of the total cost of IT assets. It was targeted at IT organisations running an in-house mode of operations. While TCO can provide a good understanding of the internal IT asset cost, it could not estimate the cost per service because the IT budget was never based on service delivery. As a result, it was neither adequate to buy external services nor sufficient to assess the value that an IT organisation can bring to the business lines. IT organisations should adopt the Total Cost of Service (TCS) model to accurately estimate services’ internal costs, benchmark the external services cost and justify the services costs in terms of business imperatives.