The To-Complete Performance Index (TCPI) is a tool in project management that is used to measure the cost performance required needed to be achieved using the remaining resources to meet a specific project management goal. In a nutshell, it is also expressed as a ratio of the cost to finish work to the remaining budget.
It is the calculated cost performance index achieved on the remainder of the work to meet a specific goal in project management like Estimate At Completion (EAC) or Budget At Completion (BAC). As one of the forecasting tools used in Control Costs, it assists the project managers when it comes to calculating the future cost performance of the project.
Simply put, this particular forecasting tool is the estimate of the organization’s future cost performance that needs to be completed within an approved and specified budget. The budget may be the initial approved budget (BAC) or the newly calculated one (EAC). Thus, the TCPI is calculated by dividing Remaining Work with the Remaining Funds (TCPI = Remaining Work / Remaining Funds). You can determine the remaining funds even if you are over or under the budget.
This term is defined in the 5th edition of the PMBOK.